Dtv transmitting system and method of processing broadcast data

ABSTRACT

A DTV transmitting system includes an encoder, a randomizer, a block processor, a group formatter, a deinterleaver, and a packet formatter. The encoder codes enhanced data for error correction, permutes the coded data, and further codes the permuted data for error detection. The randomizer randomizes the coded enhanced data, and the block processor codes the randomized data at an effective coding rate of 1/H. The group formatter forms a group of enhanced data having data regions, and inserts the coded enhanced data into at least one of the data regions. The deinterleaver deinterleaves the group of enhanced data, and the packet formatter formats the deinterleaved data into corresponding data bytes.

This application claims the benefit of the Korean Patent Application No.10-2006-0039118, filed on Apr. 29, 2006, which is hereby incorporated byreference as if fully set forth herein. Also, this application claimsthe benefit of the Korean Patent Application No. 10-2006-0089736, filedon Sep. 15, 2006, which is hereby incorporated by reference as if fullyset forth herein. This application also claims the benefit of U.S.Provisional Application No. 60/821,251, filed on Aug. 2, 2006, which ishereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to television systems and methods ofprocessing broadcast data.

2. Discussion of the Related Art

Presently, the technology for processing digital signals is beingdeveloped at a vast rate, and, as a larger number of the population usesthe Internet, digital electric appliances, computers, and the Internetare being integrated. Therefore, in order to meet with the variousrequirements of the users, a system that can transmit diversesupplemental information in addition to video/audio data through adigital television channel needs to be developed.

Some users may assume that supplemental data broadcasting would beapplied by using a PC card or a portable device having a simple in-doorantenna attached thereto. However, when used indoors, the intensity ofthe signals may decrease due to a blockage caused by the walls ordisturbance caused by approaching or proximate mobile objects.Accordingly, the quality of the received digital signals may bedeteriorated due to a ghost effect and noise caused by reflected waves.However, unlike the general video/audio data, when transmitting thesupplemental data, the data that is to be transmitted should have a lowerror ratio. More specifically, in case of the video/audio data, errorsthat are not perceived or acknowledged through the eyes or ears of theuser can be ignored, since they do not cause any or much trouble.Conversely, in case of the supplemental data (e.g., program executionfile, stock information, etc.), an error even in a single bit may causea serious problem. Therefore, a system highly resistant to ghost effectsand noise is required to be developed.

The supplemental data are generally transmitted by a time-divisionmethod through the same channel as the video/audio data. However, withthe advent of digital broadcasting, digital television receiving systemsthat receive only video/audio data are already supplied to the market.Therefore, the supplemental data that are transmitted through the samechannel as the video/audio data should not influence the conventionalreceiving systems that are provided in the market. In other words, thismay be defined as the compatibility of broadcast system, and thesupplemental data broadcast system should be compatible with thebroadcast system. Herein, the supplemental data may also be referred toas enhanced data. Furthermore, in a poor channel environment, thereceiving performance of the conventional receiving system may bedeteriorated. More specifically, resistance to changes in channels andnoise is more highly required when using portable and/or mobilereceiving systems.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a DTV transmittingsystem and a method of processing broadcast data that substantiallyobviate one or more problems due to limitations and disadvantages of therelated art.

The present invention is to provide a DTV transmitting system and amethod of processing broadcast that is suitable for transmittingadditional data and that is highly resistant to noise.

The present invention is to provide a DTV transmitting system and amethod of processing broadcast that can perform additional encoding onenhanced data and transmit the additionally encoded enhanced data,thereby enhancing the receiving quality of the receiving system.

The present invention is to provide a DTV transmitting system and amethod of processing broadcast that can multiplex the known data andenhanced data, thereby enhancing the receiving quality of the receivingsystem.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, adigital television (DTV) transmitting system includes an encoder, arandomizer, a block processor, a group formatter, a deinterleaver, and apacket formatter. The encoder codes enhanced data for error correction,permutes the coded enhanced data, and further codes the permutedenhanced data for error detection. The randomizer randomizes theenhanced data coded for error detection, and the block processor codesthe randomized enhanced data at an effective coding rate of 1/H. Thegroup formatter forms a group of enhanced data having one or more dataregions, and inserts the enhanced data coded at the effective codingrate of 1/H into at least one of the data regions. The deinterleaverdeinterleaves the group of enhanced data, and the packet formatterformats the deinterleaved enhanced data into enhanced data packets.

In another aspect of the present invention, a digital television (DTV)transmitting system includes an encoder, a data randomizing andexpanding unit, a group formatter, a block processor, a deinterleaver,and a packet formatter. The encoder codes enhanced data for errorcorrection, permutes the coded enhanced data, and further codes thepermuted enhanced data for error detection. The data randomizing andexpanding unit randomizes the enhanced data coded for error detectionand expands the randomized enhanced data at an expansion rate of 1/H.The group formatter forms a group of enhanced data having one or moredata regions, and inserts the expanded enhanced data into at least oneof the data regions. The block processor codes the enhanced data in thegroup of enhanced data at a coding rate of 1/H. The deinterleaverdeinterleaves the enhanced data coded with the coding rate of 1/H, andthe packet formatter formats the interleaved enhanced data into enhanceddata packets.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a block diagram showing a structure of a digitalbroadcast (or television or DTV) transmitting system according to anembodiment of the present invention;

FIG. 2 and FIG. 3 illustrate block diagrams of a block processor shownin FIG. 1;

FIG. 4 and FIG. 5 illustrate block diagrams of a symbol encoderaccording to the present invention;

FIG. 6 and FIG. 7 illustrate examples of a data structure at the beforeand after ends of a data deinterleaver in a digital televisiontransmitting system according to the present invention;

FIG. 8 illustrates a block diagram showing a structure of a digitalbroadcast (or television or DTV) transmitting system according toanother embodiment of the present invention;

FIG. 9 and FIG. 10 illustrate block diagrams of a block processor shownin FIG. 8;

FIG. 11 illustrates a block diagram showing a structure of ademodulating unit included a digital television receiving systemaccording to an embodiment of the present invention;

FIG. 12 illustrates a block diagram of a digital broadcast (ortelevision or DTV) transmitting system according to another embodimentof the present invention;

FIG. 13 and FIG. 14 illustrate another examples of data configuration atbefore and after ends of a data deinterleaver in a transmitting systemaccording to the present invention;

FIG. 15 illustrates a block diagram showing a general structure of ademodulating unit within a digital broadcast (or television or DTV)receiving system according to another embodiment of the presentinvention;

FIG. 16 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anembodiment of the present invention; and

FIG. 17 illustrates a block diagram showing the structure of a digitalbroadcast (or television or DTV) receiving system according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts. Within thedrawings, the same reference numerals will be used for identicalelements in different drawings. Accordingly, a detailed description ofsuch identical elements will be omitted for simplicity. In addition,although the terms used in the present invention are selected fromgenerally known and used terms, some of the terms mentioned in thedescription of the present invention have been selected by the applicantat his or her discretion, the detailed meanings of which are describedin relevant parts of the description herein. Furthermore, it is requiredthat the present invention is understood, not simply by the actual termsused but by the meaning of each term lying within.

In the present invention, the enhanced data may either consist of dataincluding information such as program execution files, stockinformation, and so on, or consist of video/audio data. Additionally,the known data refer to data already known based upon a pre-determinedagreement between the transmitting system and the receiving system.Furthermore, the main data consist of data that can be received from theconventional receiving system, wherein the main data include video/audiodata. The present invention relates to performing additional encoding onthe enhanced data, then, multiplexing the additionally encoded enhanceddata with the main data and outputting the multiplexed data, so as toprovide robustness to the enhanced data, thereby enabling the data totake strong countermeasures against the constantly changing channelenvironment. The encoding process will be described according to firstand second embodiments of the present invention.

First Embodiment

FIG. 1 illustrates a block diagram showing a structure of a digitaltelevision transmitting system according to a first embodiment of thepresent invention. Referring to FIG. 1, the digital televisiontransmitting system includes a pre-processor 110, a packet multiplexer121, a data randomizer 122, a Reed-Solomon (RS) encoder/non-systematicRS encoder 123, a data interleaver 124, a parity replacer 125, anon-systematic RS encoder 126, a trellis encoding module 127, a framemultiplexer 128, and a transmitting unit 130. The pre-processor 110includes a RS frame encoder 111, an enhanced data randomizer 112, ablock processor 113, a group formatter 114, a data deinterleaver 115,and a packet formatter 116.

In the present invention having the above-described structure, the maindata is inputted to the packet multiplexer 121, and the enhanced data isputted to the pre-processor 110 which performs additional encoding, sothat the enhanced data can take strong countermeasures against noise andthe constantly changing channel environment. The RS frame encoder 111 ofthe pre-processor 110 receives the enhanced data and configures theframe in order to perform the additional encoding. Thereafter, the RSframe encoder 111 performs the additional encoding on the enhanced dataand, then, outputs the additionally encoded enhanced data to theenhanced data randomizer 112.

For example, the RS frame encoder 111 performs at least any one of anerror correction encoding process and an error detection encodingprocess on the inputted enhanced data so as to provide the data withrobustness. In addition, the RS frame encoder 111 may also perform aprocess of permuting various sets of enhanced data having apredetermined size by dispersing burst errors that may occur due to achange in the frequency environment, thereby enabling the enhanced datato take countermeasures against a severely poor and constantly andabruptly changing frequency environment.

According to another environment of the present invention, the RS frameencoder 111 performs error correction encoding on the inputted enhanceddata, so as to add data required for error correction. Then, the RSframe encoder 111 performs a row permutation process for permuting datarow by row. Subsequently, the RS frame encoder 111 performs the errordetection encoding, thereby adding data required for error detection. Atthis point, as an example of the present invention, RS-coding is appliedfor the error correction encoding process, and a cyclic redundancy check(CRC) encoding is applied for the error detection process. Whenperforming the RS-coding, parity data that are used for the errorcorrection are generated. And, when performing the CRC encoding, CRCdata that are used for the error detection are generated.

More specifically, the RS frame encoder 111 identifies (ordistinguishes) the inputted enhanced data by units of a predeterminedlength (A). A plurality of units of the identified predetermined length(A) is grouped to form a RS frame. Thereafter, RS-coding is performed onthe newly formed RS frame along the direction of the row or column. Inthe present invention, the predetermined length (A) will be referred toas a row for simplicity of the description. Herein, the value A isdecided by the system designer.

For example, if the inputted enhanced data correspond to an MPEGtransport stream (TS) packet configured in 188-byte units, the firstMPEG synchronization byte is removed. Thereafter, a row (A) is formed onthe 187 bytes. Herein, the MPEG synchronization byte is removed so thatall enhanced data packets are given the same value. If the inputtedenhanced data do not include a removable byte, or if the inputtedenhanced data packet is not 187-byte long, the inputted data are dividedinto units of 187 bytes, so that each 187-byte data unit configures arow. A plurality of rows configured according to the above describedprocess is grouped to form a RS frame.

In the present invention, RS-coding is performed by RS frame units,thereby adding parity bytes thereto. Thereafter, a row permutationprocess is performed on the parity-byte-added RS frame. For example, aplurality (or G number) of RS frames that are RS-coded is grouped toform a group. More specifically, after performing the row permutationprocess, the i^(th) row of the RS frame group prior to the rowpermutation process, is placed to the j^(th) row of the RS frame groupafter the row permutation process. The relation between i and j is shownin Equation 1 below.

j=G(i mod S)+└i/S┘

i=S(j mod G)+└j/G┘  [Equation 1]

where 0≦i, j<SG

Herein, G represents the number of RS frames included in the RS framegroup, and S represents the value of the number of rows within the RSframe prior to the RS-coding added with the parities generated by theRS-coding process. After the row permutation process is performed, CRCencoding is performed on the row-permuted data so as to add a CRCchecksum. The CRC checksum indicates whether the enhanced data have beendamaged by an error while being transmitted through a channel. Thepresent invention may also use other error detection encoding methodsother than the CRC encoding. Alternatively, the present invention mayalso use the error correction encoding method so as to enhance theoverall error correcting ability (or function) of the DTV receivingsystem.

As described above, the CRC encoded data are outputted to the enhanceddata randomizer 112. Herein, the enhanced data randomizer 112 receivesand randomizes the enhanced data in which robustness has been enhanceddue to the encoding and row permutation. Thereafter, the randomizedenhanced data are outputted to the block processor 113. At this point,by randomizing the enhanced data in the enhanced data randomizer 112,the process of randomizing the enhanced data at the randomizer 122 in alater process may be omitted. The randomizer identical to that of theconventional ATSC or other types of randomizer may be used forrandomizing the enhanced data. More specifically, a pseudo random bytegenerated from within the inputted 187-byte enhanced data may be used torandomize the enhanced data. The block processor 113 codes therandomized enhanced data at a G/H coding rate and outputs the codedenhanced data. For example, if 1 bit of enhanced data is coded to 2 bitsand outputted, then G is equal to 1 and H is equal to 2 (i.e., G=1 andH=2). Alternatively, if 1 bit of enhanced data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).

FIG. 2 and FIG. 3 illustrate block diagrams showing examples of theblock processor 113. Referring to FIG. 2, the block processor 113includes a byte-bit converter 311, a symbol encoder 312, a symbolinterleaver 313, and a symbol-byte converter 314, and the blockprocessor 113 may perform a coding process at a 1/2-coding rate or a1/4-coding rate. More specifically, the byte-bit converter 311identifies the inputted enhanced data byte by 1-bit units and outputsthe identified enhanced data bits to the symbol encoder 312. The symbolencoder 312 codes the inputted enhanced data bit to a 2-bit symbol andoutputs the coded 2-bit symbol to the symbol interleaver 313. In thiscase, the symbol encoder 312 is operated as an encoder having a1/2-coding rate.

Meanwhile, if the symbol encoder 312 is to be operated as an encoderhaving a 1/4-coding rate, the symbol coded at a 1/2-coding rate may berepeated so as to output two symbols, or the input data bit may be codedat a 1/2-coding rate two times and outputted as two symbols. Theabove-mentioned 1/2-coding rate and 1/4-coding rate are only exemplaryembodiments proposed in the description of the present invention, andthe coding rate may vary depending upon the number of repetition.Therefore, the present invention is not limited only to the examplesproposed herein. The symbol interleaver 313 receives the output symbolof the symbol encoder 312 in symbol units so as to perform a blockinterleaving process on the received symbol, thereby outputting theprocessed symbol to the symbol-byte converter 314. The symbol-byteconverter 314 converts the output symbols of the symbol interleaver tobyte units, thereby outputting the byte-converted symbol to the groupformatter 114.

Referring to FIG. 3, the block processor 113 includes a byte-bitconverter 351, a symbol encoder 352, a parallel-to-serial converter 353,a symbol interleaver 354, and a symbol-byte converter 355, and the blockprocessor 113 may perform a coding process at a 1/2-coding rate or a1/4-coding rate. More specifically, the byte-bit converter 351identifies (or distinguishes) the inputted enhanced data byte by 1-bitunits and, then, outputs the identified bits to the symbol encoder 352.The symbol encoder 352 codes the inputted enhanced data bits to 4 bits,i.e., to two symbols, and simultaneously outputs the coded enhanced databits to the parallel-to-serial converter 353. In this case, the symbolencoder 352 operates as an encoder having a 1/4-coding rate. Theparallel-to-serial converter 353 converts the two symbols inputted inparallel to serial symbol units, thereby serially (or sequentially)outputting the two symbols to the symbol interleaver 354.

Meanwhile, if one of the two symbols coded in the symbol encoder 352 isselected and outputted, the symbol encoder 352 is operated as a1/2-coding rate encoder. Since the output is in symbol units, the outputsymbol bypasses the parallel-to-serial converter 353 and is inputted tothe symbol interleaver 354. In addition, if the symbol encoder 312repeatedly outputs two 1/2-rate coded symbols, or if the symbol encoder312 coded an input bit twice at a 1/2-coding rate, the overall codingrate becomes a 1/4-coding rate, thereby enhancing the error correctionability (or function). However, the size of the actual data that can betransmitted becomes smaller as the coding rate becomes lower. Therefore,the coding rate should be decided while taking these two factors intoconsideration.

The above-mentioned 1/2-coding rate and 1/4-coding rate are onlyexemplary embodiments proposed in the description of the presentinvention, and the coding rate may vary depending upon either theselection of the coded symbols or the number of repetition. Therefore,the present invention is not limited only to the examples proposedherein. By performing symbol-unit block interleaving, the symbolinterleaver 354 rearranges the order of the symbols outputted from theparallel-to-serial converter 353 and outputs the rearranged symbols tothe symbol-byte converter 355. The symbol-byte converter 355 convertsthe symbols outputted from the symbol interleaver 354 to byte units andoutputs the byte-converted symbols to the group formatter 114.

FIG. 4 and FIG. 5 respectively illustrate block diagrams of the symbolencoder according to the embodiments of the present invention shown inFIGS. 2 and 3. The symbol encoder shown in FIG. 4 includes two memories,one adder, and four memory states (i.e., 00, 01, 10, and 11). Referringto FIG. 4, the symbol encoder codes and outputs an inputted enhanceddata bit U to two bits C1 and C2. Herein, the enhanced data bit U isoutputted as an upper output bit C1 and simultaneously coded andoutputted as a lower output bit C2 as well. Therefore, the symbolencoder of FIG. 4 may be operated as a 1/2-coding rate encoder. If thesymbol encoder of FIG. 4 is to be used as a 1/4-coding rate encoder, theenhanced data bit U is coded to generate output bits 0102. Then, theoutput bits C1C2 are repeated so as to generate final output bitsC1C2C1C2. As another example, the enhanced data bit U is coded two timesat a 1/2-coding rate, thereby outputting final output bits of C1C2C1C2.

Alternatively, the symbol encoder of FIG. 5 includes three memories andfour adders. Therefore, it is apparent that, in FIG. 5, the symbolencoder codes and outputs an inputted enhanced data bit U to four bitsC1 to C4. Herein, the enhanced data bit U is outputted as the mostsignificant (or uppermost) output bit C1 and simultaneously coded andoutputted as lower output bits C2C3C4 as well. Therefore, the symbolencoder of FIG. 5 may be operated as a 1/4-coding rate encoder. If thesymbol encoder of FIG. 5 is to be used as a 1/2-coding rate encoder, theenhanced data bit U is coded to generate output bits C1C2C3C4. Then,only two bits (i.e., one symbol) of output bits C1C2C3C4 are selectedand outputted.

The group formatter 114 creates a data group in accordance with apre-defined rule. Thereafter, the group formatter 113 inserts theinputted enhanced data to the corresponding areas within the createddata group. At this point, the data group may be described as at leastone layered area. Herein, the type of enhanced data allocated to eacharea may vary depending upon the characteristics of each layered area.

FIG. 6 illustrates an alignment of different data sets prior to the datadeinterleaving, and FIG. 7 illustrates an alignment of different datasets after the data deinterleaving. In other words, FIG. 6 correspondsto the data structure after being data interleaved, and FIG. 7corresponds to the data structure before being data interleaved. FIG. 6illustrates an example of a data group within a data structure prior tothe data deinterleaving, the data group being divided into three layeredareas: a head area, a body area, and a tail area. Accordingly, in thedata group that is data interleaved and outputted, the head area isfirst outputted, then the body area is outputted, and the tail area isoutputted last.

FIG. 6 and FIG. 7 each show an example of 260 packets configuring thedata group. Herein, since the data interleaver operates periodically inunits of 52 packets, a 52*5n number of packets (wherein, n is aninteger) configure the data group. In addition, referring to the datagroup being inputted to the data deinterleaver, FIG. 6 illustrates anexample of the head, body, and tail areas of the data group beingconfigured so that the body area is entirely formed of the enhanced dataand is not mixed with the main data. At this point, the body area of thedata group being inputted to the data deinterleaver may be allocated sothat the body area includes either at least a portion or the entireportion of an area within the data group having the enhanced datacontinuously outputted therefrom. Herein, the body area may also includean area having the enhanced data outputted non-continuously.

The data group is divided into three areas so that each area may be useddifferently. More specifically, referring to FIGS. 6 and 7, the areacorresponding to the body is configured only of enhanced data and is notinterfered by any main data, thereby showing a highly resistantreceiving quality. On the other hand, in each of the areas correspondingto the head and the tail, the enhanced data set is alternately mixedwith the main data sets due to the output order of the interleaver.Thus, the receiving quality of the head and tail areas is relativelypoorer than that of the body area.

Furthermore, when using a system inserting and transmitting the knowndata to the data group, and when a long and continuous set of known datais to be inserted periodically in the enhanced data, the known data maybe inserted in an area in which the enhanced data are not mixed with themain data based upon the output order from the data interleaver. Morespecifically, in the body area of FIGS. 6 and 7, a predetermined lengthof known data may be periodically inserted in the body area. However, itis difficult to periodically insert the known data in the head area andthe tail area, and it is also difficult to insert a long and continuousset of known data. Therefore, the group formatter 114 inserts theenhanced data inserted in the corresponding area within theabove-described data group.

For example, the group formatter 114 allocates the received enhanceddata to the body area. And, apart from the enhanced data, the groupformatter 114 also separately allocates signaling information indicatingthe overall transmission information to the body area. In other words,the signaling information corresponds to information required by thereceiving system for receiving and processing the data included datagroup. Herein, the signaling information includes data groupinformation, multiplexing information, and so on. Furthermore, as shownin FIG. 6, the group formatter 114 also inserts an MPEG header placeholder, a non-systematic RS parity place holder, and a main data placeholder in relation with the data deinterleaving. Referring to FIG. 6,the main data place is allocated because the enhanced data and the maindata are alternately mixed in the head and tail areas based upon theinput of the data deinterleaver. In the output data that have been datadeinterleaved, the place holder for the MPEG header is allocated to thevery beginning of each packet.

The group formatter 114 either inserts the known data generated by apre-decided method in a corresponding area, or inserts a known dataplace holder in a corresponding area so as to insert the known data in alater process. Moreover, a place holder for initializing the trellisencoder 145 is inserted in the corresponding area. For example, theinitialization data place holder may be inserted in front of the knowndata sequence. The data group having either the data or the place holderinserted therein by the group formatter 114 is inputted to the datadeinterleaver 115. Referring to FIG. 6, whenever required in a laterprocess, the head and tail areas may be used for the enhanced data orother information data or data used for supporting the enhanced data.

The data deinterleaver 115 performs an inverse process of the datainterleaver on the inputted data group and, then, outputs thedeinterleaved data group to the packet formatter 116. More specifically,when the data group having the format shown in FIG. 6 is inputted to thedata deinterleaver 115, the data group is deinterleaved, as shown inFIG. 7, and outputted to the packet formatter 116. Herein, only theportions corresponding to the data group are shown in FIG. 7. Among thedeinterleaved and inputted data, the packet formatter 116 removes themain data place holder and the RS parity place holder that have beenallocated for the deinterleaving process. Then, the packet formatter 116gathers (or groups) the remaining portion of the input data and insertsthe remaining data to the 4-byte MPEG header place holder in place ofthe MPEG header. Furthermore, when the known data place holder isinserted by the group formatter 114, the packet formatter 116 known datamay be inserted in place of the known data place holder. Alternatively,the known data place holder may be directly outputted without anymodification for the replacement insertion in a later process.

Thereafter, the packet formatter 116 configures the data within the datagroup packet that is formatted as described above, as a 188-byte unitMPEG TS packet. Then, the packet formatter 116 provides the configured188-byte unit MPEG TS packet to the packet multiplexer 121. The packetmultiplexer 121 multiplexes the 188-byte enhanced data packet and themain data packet outputted from the packet formatter 116 according to apre-defined multiplexing method. Then, the multiplexed packets areoutputted to the data randomizer 122. The multiplexing method may bealtered or modified by various factors in the design of the system.

In a multiplexing method of the packet multiplexer 121, an enhanced databurst section and a main data section are distinguished (or identified)along a time axis, then the two sections are set to be repeatedalternately. At this point, in the enhanced data burst section, at leastone of the data groups may be transmitted, and only the main data may betransmitted in the main data section. In the enhanced data burstsection, the main data may also be transmitted. When the enhanced dataare transmitted in the above-described burst structure, the DTVreceiving system receiving only the enhanced data may turn on the poweronly during the enhanced data burst section. Alternatively, in the maindata section whereby only the main data are transmitted, the power isturned off during the main data section, thereby preventing the maindata from being received. Thus, excessive power consumption of the DTVreceiving system may be reduced or prevented. As described above, thepacket multiplexer 121 receives the main data packet and the enhanceddata packet, which is outputted from the packet formatter, and transmitsthe received packets in a burst structure.

When the inputted data correspond to the main data packet, the datarandomizer 122 performs a randomizing process identical to that of theconventional randomizer. More specifically, the MPEG synchronizationbyte within the main data packet is discarded (or deleted). Then, theremaining 187 bytes are randomized by using a pseudo random bytegenerated from within the data randomizer 122. Subsequently, therandomized data bytes are outputted to the RS encoder/non-systematic RSencoder 123.

However, when the inputted data correspond to the enhanced data packet,the MPEG synchronization byte among the four bytes included in theenhanced data packet is discarded (or deleted) and only the remaining 3bytes are randomized. The remaining portion of the enhanced dataexcluding the MPEG header is not randomized and outputted directly tothe RS encoder/non-systematic RS encoder 123. This is because arandomizing process has already been performed on the enhanced data inthe enhanced data randomizer 112. The RS encoder/non-systematic RSencoder 123 RS-codes the data randomized by the data randomizer 122 orthe data bypassing the data randomizer 122. Then, the RSencoder/non-systematic RS encoder 123 adds a 20-byte RS parity to thecoded data, thereby outputting the RS-parity-added data to the datainterleaver 124.

At this point, if the inputted data correspond to the main data packet,the RS encoder/non-systematic RS encoder 123 performs a systematicRS-coding process identical to that of the conventional broadcast systemon the inputted data, thereby adding the 20-byte RS parity at the end ofthe 187-byte data. Alternatively, if the inputted data correspond to theenhanced data packet, each place of the 20 parity bytes is decidedwithin the packet. Thereafter, the bytes of RS parity gained byperforming the non-systematic RS-coding are respectively inserted in thedecided parity byte places. Herein, the data interleaver 124 correspondsto a byte unit convolutional interleaver. The output of the datainterleaver 124 is inputted to the parity replacer 125 and thenon-systematic RS encoder 126.

Meanwhile, a memory within the trellis encoding module 127 should firstbe initialized in order to allow the output data of the trellis encodingmodule 127, which is positioned after the parity replacer 125, to becomethe known data defined based upon an agreement between the receivingsystem and the transmitting system. More specifically, the memory of thetrellis encoding module 127 should first be initialized before the knowndata sequence being inputted is encoded. At this point, the beginning ofthe known data sequence that is inputted corresponds to theinitialization data place holder included by the group formatter 114 andnot the actual known data. Therefore, a process of generatinginitialization data right before the trellis-encoding of the known datasequence being inputted and a process of replacing the initializationdata place holder of the corresponding trellis encoder memory with thenewly generated initialization data are required. This is to ensure thebackward-compatibility with the conventional receiving system.

Additionally, the value of the trellis memory initialization data isdecided in accordance with a previous state of the memory in the trellisencoding module 127, and the initialization data are generatedaccordingly. Furthermore, due to the replaced initialization data, aprocess of recalculating the RS parity and a process of replacing thenewly calculated RS parity with the RS parity outputted from the datainterleaver 124 are required. Therefore, the non-systematic RS encoder126 receives the enhanced data packet including the initialization dataplace holder that is to be replaced with the initialization data fromthe data interleaver, and the non-systematic RS encoder 126 receives theinitialization data from the trellis encoding module 127. Then, thenon-systematic RS encoder 126 calculates a new non-systematic RS parityand outputs the newly calculated non-systematic RS parity to the parityreplacer 125. Thereafter, the parity replacer 125 selects the output ofthe data interleaver 124 as the data within the enhanced data packet,and the parity replacer 125 selects the output of the non-systematic RSencoder 126 as the RS parity.

Meanwhile, when the main data packet is inputted or when the enhanceddata packet, which does not include the initialization data place holderthat is to be replaced, is inputted, the parity replacer 125 selects thedata outputted from the data interleaver 124 and the RS parity andoutputs the selects output data and RS parity to the trellis encodingmodule 127 without any modification. The trellis encoding module 127modifies the byte-unit data to symbol-unit data. Then, the trellisencoding module 127 12-way interleaves and trellis-encodes the modifieddata, so as to output the processed data to the frame multiplexer 128.The frame multiplexer 128 inserts field and segment synchronizationsignals in the output of the trellis encoding module 127 and outputs theprocessed data to the transmitting unit 130. Herein, the transmittingunit 130 includes a pilot inserter 131, a modulator 132, and a radiofrequency (RF) up-converter 133. The transmitting unit 130 operatesidentically as in the conventional transmitting system. Therefore, adetailed description of the same will be omitted for simplicity.

Second Embodiment

FIG. 8 illustrates a block diagram showing a structure of a digitaltelevision transmitting system according to a second embodiment of thepresent invention.

Referring to FIG. 5, the digital television transmitting system includesa pre-processor 510, a packet multiplexer 121, a data randomizer 122, aReed-Solomon (RS) encoder/non-systematic RS encoder 123, a datainterleaves 124, a parity replacer 125, a non-systematic RS encoder 126,a trellis encoding module 127, a frame multiplexer 128, and atransmitting unit 130. The pre-processor 510 includes a RS frame encoder511, a randomizer/byte expander 512, a group formatter 513, a blockprocessor 514, a data deinterleaver 515, and a packet formatter 516.

The difference between the digital television transmitting system shownin FIG. 1 and the digital television transmitting system shown in FIG. 8is the arrangement order of the group formatter and the block processor.In FIG. 1, the group formatter 114 is placed after the block processor113, whereas the block processor 514 is placed after the group formatter513. More specifically, in the digital television transmitting systemshown in FIG. 5, since the group formatter 513 is placed before theblock processor 514, for a smooth operation of the group formatter 513,a byte expansion process is required to be performed before theoperation of the group formatter 513 so that the group formatter 513 maycorrespond with the coding process of the block processor 514.Therefore, in the digital television transmitting system shown in FIG.5, the randomizer/byte expander 512 not only performs a randomizingprocess but also performs a byte expansion process by inserting nulldata bytes.

Conversely, in the digital television transmitting system shown in FIG.1, the block processor 113 is placed before the group formatter 114.Accordingly, since expansion is performed by the coding process of theblock processor 113, a separate byte expansion process is not necessary.Therefore, in FIG. 1, only a randomizing process is performed on theenhanced data and a byte expansion process is not performed.Hereinafter, the pre-processor 510 will be described in detail withreference to FIG. 5. Since the other blocks (i.e., reference numerals121 to 128 and 130) may be applied identically as those of FIG. 1, thedetailed description of the same will be omitted for simplicity.

The enhanced data are inputted to the pre-processor 510 which performsadditional encoding, so that the enhanced data can take strongcountermeasures against noise and the constantly changing channelenvironment. The RS frame encoder 511 of the pre-processor 510 receivesthe enhanced data and configures the frame in order to perform theadditional encoding. Thereafter, the RS frame encoder 511 performs theadditional encoding on the enhanced data and, then, outputs theadditionally encoded enhanced data to the randomizer/byte expander 512.

The RS frame encoder 511 performs at least any one of an errorcorrection encoding process and an error detection encoding process onthe inputted enhanced data so as to provide the data with robustness. Inaddition, the RS frame encoder 511 may also perform a process ofpermuting various sets of enhanced data having a predetermined size bydispersing burst errors that may occur due to a change in the frequencyenvironment, thereby enabling the enhanced data to take countermeasuresagainst a severely poor and constantly and abruptly changing frequencyenvironment.

As an example, the RS frame encoder 511 performs error correctionencoding on the inputted enhanced data, so as to add data required forerror correction. Then, the RS frame encoder 511 performs a rowpermutation process for permuting data row by row. Subsequently, the RSframe encoder 511 performs the error detection encoding, thereby addingdata required for error detection. At this point, as an example of thepresent invention, RS-coding is applied for the error correctionencoding process, and a cyclic redundancy check (CRC) encoding isapplied for the error detection process. When performing the RS-coding,parity data that are used for the error correction are generated andadded. And, when performing the CRC encoding, CRC data that are used forthe error detection are generated and added. Each of the RS-coding, rowpermutation, and CRC encoding processes are identical to those mentionedin FIG. 1, and therefore, a detailed description of the same will beomitted for simplicity.

The randomizer/byte expander 512 receives and randomizes the enhanceddata in which robustness has been enhanced due to the encoding and rowpermutation. Herein, a byte expansion process is also performed on theenhanced data by inserting null data bytes. At this point, byrandomizing the enhanced data in the randomizer/byte expander 512, theprocess of randomizing the enhanced data at the randomizer 122 in alater process may be omitted. The randomizer identical to that of theconventional ATSC or other types of randomizer may be used forrandomizing the enhanced data. More specifically, a pseudo random bytegenerated from within the inputted 187-byte enhanced data may be used torandomize the enhanced data.

Additionally, the order of the randomizing process and the byteexpansion process may be altered. In other words, the randomizingprocess may first be performed as described above, which is thenfollowed by the byte expansion process. Alternatively, the byteexpansion process may first be performed, which is then followed by therandomizing process. The order of the processes may be selected inaccordance with the overall structure of the system.

The byte expansion process may vary depending upon the coding rate ofthe block processor 514. More specifically, if the coding rate of theblock processor 514 corresponds to a G/H coding rate, then the byteexpander expands G bytes to H bytes. For example, if the coding ratecorresponds to 1/2 coding rate, then 1 byte is expanded to 2 bytes. And,if the coding rate is 1/4, then 1 byte is expanded to 4 bytes. Theenhanced data outputted from the randomizer/byte expander 512 areinputted to the group formatter 513. The group formatter 513 creates adata group, as shown in FIG. 1, and then inserts the inputted enhanceddata to the corresponding areas within the created data group. At thispoint, the data group may be described as at least one layered area.Herein, the type of enhanced data allocated to each area may varydepending upon the characteristics of each layered area.

In the present invention, the data group is divided into three layeredareas: a head area, a body area, and a tail area. More specifically, inthe data group that is data interleaved and outputted, the head area isfirst outputted, then the body area is outputted, and the tail area isoutputted last. At this point, the body area of the data group beinginputted to the data deinterleaver may be allocated so that the bodyarea includes either at least a portion or the entire portion of an areawithin the data group having the enhanced data continuously outputtedtherefrom. Herein, the body area may also include an area having theenhanced data outputted non-continuously.

Therefore, the group formatter 513 inserts the enhanced data inserted inthe corresponding area within the above-described data group. Forexample, the group formatter 513 allocates the received enhanced data tothe body area. And, apart from the enhanced data, the group formatter513 also separately allocates signaling information indicating theoverall transmission information to the body area. In other words, thesignaling information corresponds to information required by thereceiving system for receiving and processing the data included datagroup. Herein, the signaling information includes data groupinformation, multiplexing information, and so on. Furthermore, the groupformatter 513 also inserts an MPEG header place holder, a non-systematicRS parity place holder, and a main data place holder in relation withthe data deinterleaving.

The block processor 514 performs additional encoding only on theenhanced data outputted from the group formatter 513. For example, if a2-byte expansion has been performed in the randomizer/byte expander 512,the block processor 514 encodes the enhanced data at a 1/2 coding rate.Alternatively, if a 4-byte expansion has been performed in therandomizer/byte expander 512, the block processor 514 encodes theenhanced data at a 1/4 coding rate. In addition, the MPEG header placeholder, the main data place holder, and the RS parity place holder areoutputted directly without any modifications. Furthermore, the knowndata (or known data place holder) and the initialization data placeholder may be directly outputted without modification or replaced withthe known data generated from the block processor 514 and thenoutputted. The method of directly outputting the data or data holderwithout any modification is shown in FIG. 9, and the method of replacingthe data or data holder with the known data is shown in FIG. 10.

Referring to FIG. 9, the block processor 514 includes a demultiplexer610, a buffer 620, an enhanced encoder 630, a known data (or sequence)generator 640, and a multiplexer 650. The enhanced encoder 630 includesa byte-symbol converter 631, a symbol encoder 632, a parallel-to-serialconverter 633, a symbol interleaver 634, and a symbol-byte converter635. In FIG. 9, when the inputted data correspond to the main data placeholder, the MPEG header place holder, and the RS parity place holder,the demultiplexer 610 outputs the input data to the buffer 620. On theother hand, if the input data correspond to the enhanced data, thedemultiplexer 610 outputs the input data to the enhanced encoder 630.The buffer 620 delays the main data place holder, the MPEG header placeholder, and the RS parity place holder for a predetermined period oftime and outputs the delayed place holders to the multiplexer 640. Morespecifically, when the data inputted to the demultiplexer 610 correspondto the main data place holder, the MPEG header place holder, and the RSparity place holder, a difference in time occurs while the enhanced dataundergo an additional encoding process. Herein, the buffer 620 is usedto delay the input data as much as the time difference and to compensatefor the delayed data. The data having the time difference adjusted bythe buffer 620 are then transmitted to the data deinterleaver 515through the multiplexer 640.

Alternatively, when the data inputted to the demultiplexer 610correspond to the known data, a known data place holder is inserted fromthe group formatter 513. Then, by selecting a training sequence Toutputted from the known data generator 640 instead of the known dataplace holder from the multiplexer 650 of the block processor 514, theknown data is outputted without any additional encoding. At this point,the initialization data place holder inserted from the group formatter513 may be directly outputted, or the known data outputted from theknown data generator 640 may be outputted instead of the initializationdata place holder. Herein, the known data outputted instead of theinitialization data place holder may be replaced with an initializationsymbol at the trellis encoding module 127.

Meanwhile, the byte-symbol converter 631 of the enhanced encoder 630converts an enhanced data byte to 4 symbols, which are then outputted tothe symbol encoder 632. Herein, the symbol encoder 632 is operated as aG/H coding rate encoder encoding G bits of enhanced data to H bits. Forexample, if 1 bit of enhanced data is coded to 2 bits and outputted,then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of enhanced data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).The symbol encoder 632 only encodes and outputs input symbol bits havingvalid data included therein.

For example, assuming that 1 enhanced data byte is expanded to 2 bytesby inserting a null data bit in between the enhanced data bits at therandomizer/byte expander 512, the symbol encoder 632 may code only thevalid data bit among the symbol configured of a null data bit and avalid data bit so as to output 2 bits. In this case, the encoder isoperated as a 1/2-coding rate encoder. Alternatively, assuming that 1enhanced data byte is expanded to 4 bytes by inserting null data bits inbetween the enhanced data bits at the randomizer/byte expander 512, thesymbol encoder 632 may code only the valid data bit among the 2 symbolsconfigured of 3 null data bits and a valid data bit so as to output 4bits. Furthermore, as another example, only the valid data bit among thesymbol configured of a null data bit and a valid data bit may be codedso as to create 2 bits. Thereafter, the 2 coded bits may be repeated soas to create 4 final output bits. Finally, only the valid data bit amongthe symbol configured of a null data bit and a valid data bit may becoded two times at a 1/2-coding rate. Accordingly, when the codedsymbols are outputted, 4 final bits may be outputted. In all of theabove described cases, the encoder is operated as a 1/4-coding rateencoder. More specifically, the enhanced data length is identical atboth the inputting end and outputting end of the symbol encoder 632.Further, the error correction is more effective when the valid data bitis outputted at a 1/4-coding rate than when outputted at a 1/2-codingrate.

FIG. 4 and FIG. 5 may be applied to the symbol encoder 632. However, inthis case, the input bit U of FIGS. 4 and 5 corresponds to the bithaving the valid data among the input symbol. In other words, if thesymbol encoder of FIGS. 4 and 5 is designed to code only the valid databit among the input symbol, the same symbol encoder may be applied toFIG. 9 and FIG. 10. If one enhanced data byte is expanded to 2 bytes inthe randomizer/byte expander 512, the valid data bit is inputted by onesymbol unit. Alternatively, one enhanced data byte is expanded to 4bytes in the randomizer/byte expander 512, the valid data bit isinputted by two symbol units.

If the symbol encoder 632 is operated as a 1/2-rate encoder, the outputof the symbol encoder 632 directly bypasses the parallel-to-serialconverter 633 and is inputted to the symbol interleaver 634. In thiscase, the parallel-to-serial converter 633 may be omitted.Alternatively, if the symbol encoder 632 is operated as a 1/4-rateencoder, the output of the symbol encoder 632 is inputted to theparallel-to-serial converter 633, thereby being converted to a serialsymbol, and then inputted to the symbol interleaver 634. This isbecause, when the symbol encoder 632 is operated as a 1/4-rate encoder,2 symbols (i.e., 4 bits) are outputted in parallel from the symbolencoder, and also because the symbol interleaver 634 performsinterleaving by a 1-symbol unit (i.e., a 2-bit symbol). Therefore, thetwo symbols being inputted in parallel to the parallel-to-serialconverter 633 in converted to two serial symbols, thereby sequentiallyoutputting the two symbols to the symbol interleaver 634.

The symbol interleaver 634 receives the output of the parallel-to-serialconverter 633, so as to rearrange the symbol order by performing blockinterleaving in symbol units, thereby outputting the rearranged symbolsto the symbol-byte converter 635. The symbol-byte converter 635 convertsthe output symbols of the symbol interleaver 634 to byte units andoutputs the byte-converted symbols to the multiplexer 650. When the datainputted to the multiplexer 650 correspond to the main data placeholder, the MPEG header place holder, and the RS parity place holder,the multiplexer 650 selects the data outputted from the buffer 620. Onthe other hand, when the data inputted to the multiplexer 650 correspondto the enhanced data the multiplexer 650 selects the enhanced data codedand outputted from the enhanced encoder 630. Further, when the datainputted to the multiplexer 650 correspond to the known data placeholder (or known data), the multiplexer 650 selects the trainingsequence T that outputted from the known data generator 640 instead ofthe known data place holder and, then, outputs the selected data to thedata deinterleaver 515.

FIG. 10 is very similar to FIG. 9. However, the difference between thetwo drawings in the known data processing part. More specifically,referring to FIG. 10, when the data inputted to the demultiplexer 660correspond to the known data, the demultiplexer 660 outputs the inputteddata to the buffer 670, so as to delay the data for a predeterminedperiod of time. Thereafter, the demultiplexer 660 outputs the delayeddata to the data deinterleaver 114 through the multiplexer 680. Theremaining parts of FIG. 10 are identical to those of FIG. 9, andtherefore, detailed description of the same will be omitted forsimplicity. In this case, it is assumed that the known data are alreadyinserted in the enhanced data packet by the group formatter 513.

As described above, the data being coded, replaced, and bypassed by theblock processor 514 are inputted to the data interleaver 515.Thereafter, the data interleaver 515 performs an inverse process of thedata interleaver 124 by deinterleaving the inputted data and outputtingthe deinterleaved data to the packet formatter 516. The packet formatter516 receives the data outputted from the data deinterleaver 515.Subsequently, the data deinterleaver 515 removes the main data placeholder and the RS parity place holder, which were allocated for thedeinterleaving process, from the deinterleaved input data. Then, thedata deinterleaver 515 gathers (or groups) the remaining portion of thedeinterleaved data and inserts MPEG headers in the place of the 4-byteMPEG header place holder.

The packet formatter 516 configures the packet-formatted data to a188-byte MPEG TS packet and provides the 188-byte MPEG TS packet to thepacket multiplexer 121. The packet multiplexer 121 multiplexes the188-byte enhanced data packet outputted from the packet formatter 516and the main data packet, thereby outputting the multiplexed data to thedata randomizer 122. The multiplexing method will be described in detailwith reference to FIG. 1. The remaining process steps are identical tothose of FIG. 1, and the detailed description of the same will,therefore, be omitted for simplicity.

FIG. 11 illustrates an example of a demodulating unit included a digitalbroadcast receiving system receiving data transmitted by theabove-described digital broadcast transmitting system, therebyrecovering the received data to its initial state by demodulating andequalizing the received data. Referring to FIG. 11, the demodulatingunit according to the present invention includes a demodulator 701,equalizer 702, a known sequence detector 703, a block decoder 704, anenhanced data deformatter 705, a RS frame decoder 706, a datadeinterleaver 707, a RS decoder 708, and a main data derandomizer 709.

More specifically, the received signal through a tuner inputs to thedemodulator 701 and the known sequence detector 703. The demodulator 701performs automatic gain control, carrier recovery and timing recovery,etc., for the inputted signal to generate a baseband signal, and thenoutput it to the equalizer 702 and the known sequence detector 703. Theequalizer 702 compensates the distortion of the channel included in thedemodulated signal and then outputs the error-compensated signal to theblock decoder 704.

At this point, the known sequence detector 703 detects the known datasequence place inserted by the transmitting end from the input/outputdata of the demodulator 701 (i.e., the data prior to the demodulation orthe data after the modulation). Thereafter, the place information alongwith the symbol sequence of the known sequence, which is generated fromthe detected place, is outputted to the demodulator 701, the equalizer702, and the block decoder 704. Further, the known sequence detector 703outputs information related to the enhanced data additionally encoded bythe transmitting end and the main data that have not been additionallyencoded to the block decoder 704. Herein, the outputted information isoutputted to allow the enhanced data and the main data to bedifferentiated by the block decoder 704 of the receiving end and to findout the starting point of a block in the enhanced encoder. Although theconnection state is not shown in FIG. 11, the information detected bythe known sequence detector 703 may be used throughout almost the entirereceiving system. Herein, the detected information may also be used inthe enhanced data deformatter 705 and in the RS frame decoder 706.

The demodulator 701 uses the known data symbol sequence during thetiming and/or carrier recovery, thereby enhancing the demodulatingquality. Similarly, the equalizer 702 uses the known data sequence,thereby enhancing the equalizing quality. Furthermore, the decodingresult of the block decoder 704 may also be fed-back to the equalizer702, thereby enhancing the equalizing quality.

Meanwhile, when the data being inputted to the block decoder 704correspond to the enhanced data being additionally coded andtrellis-encoded by the transmitting end, the equalizer 702 performs aninverse process of the transmitting end by additionally decoding andtrellis-decoding the inputted enhanced data. On the other hand, when thedata being inputted correspond to the main data being trellis-encodedonly and not additionally coded, the equalizer 702 only performstrellis-decoding on the inputted main data. The data group decoded bythe block decoder 704 is inputted to the enhanced data deformatter 705,and the trellis-encoded data are inputted to the data deinterleaver 707.More specifically, when the inputted data correspond to the main data,the block decoder 704 performs Viterbi-decoding on the input data so asto output a hard decision value or to perform hard decision on a softdecision value and output the hard-decided result. Meanwhile, when theinputted data correspond to the enhanced data, the block decoder 704outputs a hard decision value or a soft decision value on the inputtedenhanced value.

When the inputted data correspond to the enhanced data, the blockdecoder 704 performs a decoding process on the data encoded by the blockprocessor 113 or 514 and trellis encoding module 127 of the DTVtransmitting system. At this point, the data outputted from the RS frameencoder 111 or 511 of the pre-processor 110 or 510 included in the DTVtransmitting system may correspond to an external code, and the dataoutputted from each of the block processor 113 or 514 and the trellisencoding module 127 may correspond to an internal code.

When decoding such concatenated codes, the decoder of the internal codeshould output a soft decision value, so that the external codingperformance can be enhanced. Therefore, the block decoder 704 may alsooutput a hard decision value on the enhanced data and, preferably, asoft decision value may be outputted when required. More specifically,any one of a soft decision value and a hard decision value is outputtedwith respect to the enhanced data depending upon the overall design orconditions of the system, and a hard decision value is outputted withrespect to the main data.

Meanwhile, the data deinterleaver 707, the RS decoder 708, and the maindata derandomizer 709 are blocks required for receiving the main data.Therefore, these blocks may not be required in the structure of a DTVreceiving system that only receives the enhanced data. The datadeinterleaver 707 performs an inverse process of the data interleaverincluded in the DTV transmitting system. More specifically, the datadeinterleaver 707 deinterleaves the main data and outputs thedeinterleaved data to the RS decoder 708. The RS decoder 708 performs RSdecoding on the deinterleaved data and outputs the RS-decoded data tothe main data derandomizer 709. The main data derandomizer 709 receivesthe output of the RS decoder 708 and generates a pseudo random data byteidentical to that of the randomizer included in the DTV transmittingsystem. Thereafter, the main data derandomizer 709 performs a bitwiseexclusive OR (XOR) operation on the generated pseudo random data byte,thereby inserting the MPEG synchronization bytes to the beginning ofeach packet so as to output the data in 188-byte main data packet units.

The data being outputted from the block decoder 704 are inputted to theenhanced data deformatter 705 in the format of the data group, as shownin FIG. 6. At this point, the enhanced data deformatter 705 alreadyknows the configuration of the input data. Therefore, the signalinginformation having the system information and enhanced data aredifferentiated in the body area within the data group. In addition, theenhanced data deformatter 705 removes the known data, trellisinitialization data, and MPEG header that were inserted in the main dataand data group and also removes the RS parity added by one of the RSencoder/non-systematic RS encoder 123 and non-systematic RS encoder 126of the DTV transmitting system.

Furthermore, a derandomizing process is performed as an inverse processof the randomizer (shown in FIG. 1) or the randomizer/byte expander(shown in FIG. 5) in the DTV transmitting system on the enhanced data.At this point, the null data byte used for the byte expansion by thebyte expander may be or may not be required to be removed. In otherwords, depending upon design of the DTV receiving system, the removal ofthe byte, which has been expanded by the byte expander of the DTVtransmitting system, may be required. However, if the null data byteinserted during the byte expansion is removed and outputted by the blockdecoder 704, the expanded byte is not required to be removed. However,if the removal of the expanded byte is required, the order of the byteremoval process and the derandomizing process may vary depending uponthe structure of the DTV transmitting system. More specifically, if thebyte expansion is performed after the randomizing process in the DTVtransmitting system, then the byte removal process is first performedbefore performing the derandomizing process in the DTV receiving system.Conversely, if the order of the process is changed in the DTVtransmitting system, the order of the respective processes in the DTVreceiving system is also changed.

When performing the derandomizing process, if the RS frame decoder 706requires a soft decision in a later process, and if, therefore, theblock decoder 704 receives a soft decision value it is difficult toperform an XOR operation between the soft decision and the pseudo randombit, which is used for the derandomizing process. Accordingly, when anXOR operation is performed between the pseudo random bit and the softdecision value of the enhanced data bit, and when the pseudo random bitis equal to ‘1’, the enhanced data deformatter 705 changes the code ofthe soft decision value and then outputs the changed code. On the otherhand, if the pseudo random bit is equal to ‘0’, the enhanced datadeformatter 705 outputs the soft decision value without any change inthe code. Thus, the state of the soft decision may be maintained andtransmitted to the RS frame decoder 706.

If the pseudo random bit is equal to ‘1’ as described above, the code ofthe soft decision value is changed because, when an XOR operation isperformed between the pseudo random bit and the input data in therandomizer of the transmitting system, and when the pseudo random bit isequal to ‘1’, the code of the output data bit becomes the opposite ofthe input data (i.e., 0 XOR 1=1 and 1 XOR 0=0). More specifically, ifthe pseudo random bit generated from the enhanced data deformatter 705is equal to ‘1’, and when an XOR operation is performed on the harddecision value of the enhanced data bit, the XOR-operated value becomesthe opposite value of the hard decision value. Therefore, when the softdecision value is outputted, a code opposite to that of the softdecision value is outputted.

The RS frame decoder 706 performs an inverse process of the RS frameencoder 111 in the DTV transmitting system. More specifically, byperforming at least any one of the error detection decoding, theinversed row permutation, and the error correction decoding processes,the enhanced data may be recovered to its initial state.

FIG. 12 illustrates a block diagram showing the structure of a digitalbroadcast transmitting system according to an embodiment of the presentinvention. The digital broadcast(or DTV) transmitting system includes apre-processor 710, a packet multiplexer 721, a data randomizer 722, aReed-Solomon (RS) encoder/non-systematic RS encoder 723, a datainterleaver 724, a parity byte replacer 725, a non-systematic RS encoder726, a frame multiplexer 728, and a transmitting system 730. Thepre-processor 710 includes an enhanced data randomizer 711, a RS frameencoder 712, a block processor 713, a group formatter 714, a datadeinterleaver 715, and a packet formatter 716.

In the present invention having the above-described structure, main dataare inputted to the packet multiplexer 721. Enhanced data are inputtedto the enhanced data randomizer 711 of the pre-processor 710, wherein anadditional coding process is performed so that the present invention canrespond swiftly and appropriately against noise and change in channel.The enhanced data randomizer 711 randomizes the received enhanced dataand outputs the randomized enhanced data to the RS frame encoder 712. Atthis point, by having the enhanced data randomizer 711 perform therandomizing process on the enhanced data, the randomizing process on theenhanced data by the data randomizer 722 in a later process may beomitted. Either the randomizer of the conventional broadcast system maybe used as the randomizer for randomizing the enhanced data, or anyother type of randomizer may be used herein.

The RS frame encoder 712 receives the randomized enhanced data andperforms at least one of an error correction coding process and an errordetection coding process on the received data. Accordingly, by providingrobustness to the enhanced data, the data can scatter group error thatmay occur due to a change in the frequency environment. Thus, the datacan respond appropriately to the frequency environment which is verypoor and liable to change. The RS frame multiplexer 712 also includes aprocess of mixing in row units many sets of enhanced data each having apre-determined size. By performing an error correction coding process onthe inputted enhanced data, the RS frame encoder 712 adds data requiredfor the error correction and, then, performs an error detection codingprocess, thereby adding data required for the error detection process.The error correction coding uses the RS coding method, and the errordetection coding uses the cyclic redundancy check (CRC) coding method.When performing the RS coding process, parity data required for theerror correction are generated. And, when performing the CRC codingprocess, CRC data required for the error detection are generated.

The RS frame encoder 712 performs CRC coding on the RS coded enhanceddata in order to create the CRC code. The CRC code that is generated bythe CRC coding process may be used to indicate whether the enhanced datahave been damaged by an error while being transmitted through thechannel. The present invention may adopt other types of error detectioncoding methods, apart from the CRC coding method, and may also use theerror correction coding method so as to enhance the overall errorcorrection ability of the receiving system. For example, assuming thatthe size of one RS frame is 187*N bytes, that (235,187)-RS codingprocess is performed on each column within the RS frame, and that a CRCcoding process using a 2-byte (i.e., 16-bit) CRC checksum, then a RSframe having the size of 187*N bytes is expanded to a RS frame of235*(N+2) bytes. The RS frame expanded by the RS frame encoder 712 isinputted to the block processor 713. The block processor 713 codes theRS-coded and CRC-coded enhanced data at a coding rate of G/H. Then, theblock processor 713 outputs the G/H-rate coded enhanced data to thegroup formatter 714. In order to do so, the block processor 713identifies the block data bytes being inputted from the RS frame encoder712 as bits.

The block processor 713 may receive supplemental information data suchas signaling information, which include information on the system, andidentifies the supplemental information data bytes as data bits. Herein,the supplemental information data, such as the signaling information,may equally pass through the enhanced data randomizer 711 and the RSframe encoder 712 so as to be inputted to the block processor 713.Alternatively, the supplemental information data may be directlyinputted to the block processor 713 without passing through the enhanceddata randomizer 711 and the RS frame encoder 712. The signalinginformation corresponds to information required for receiving andprocessing data included in the data group in the receiving system. Suchsignaling information includes data group information, multiplexinginformation, and burst information.

As a G/H-rate encoder, the block processor 713 codes the inputted dataat a coding rate of G/H and then outputs the G/H-rate coded data. Forexample, if 1 bit of the input data is coded to 2 bits and outputted,then G is equal to 1 and H is equal to 2 (i.e., G=1 and H=2).Alternatively, if 1 bit of the input data is coded to 4 bits andoutputted, then G is equal to 1 and H is equal to 4 (i.e., G=1 and H=4).As an example of the present invention, it is assumed that the blockprocessor 713 performs a coding process at a coding rate of 1/2 (alsoreferred to as a 1/2-rate coding process) or a coding process at acoding rate of 1/4 (also referred to as a 1/4-rate coding process). Morespecifically, the block processor 713 codes the received enhanced dataand supplemental information data, such as the signaling information, ateither a coding rate of 1/2 or a coding rate of 1/4. Thereafter, thesupplemental information data, such as the signaling information, areidentified and processed as enhanced data.

Since the 1/4-rate coding process has a higher coding rate than the1/2-rate coding process, greater error correction ability may beprovided. Therefore, in a later process, by allocating the 1/4-ratecoded data in an area with deficient receiving performance within thegroup formatter 714, and by allocating the 1/2-rate coded data in anarea with excellent receiving performance, the difference in the overallperformance may be reduced. More specifically, in case of performing the1/2-rate coding process, the block processor 713 receives 1 bit andcodes the received 1 bit to bits (i.e., 1 symbol). Then, the blockprocessor 713 outputs the processed 2 bits (or 1 symbol). On the otherhand, in case of performing the 1/4-rate coding process, the blockprocessor 713 receives 1 bit and codes the received 1 bit to 4 bits(i.e., 2 symbols). Then, the block processor 713 outputs the processed 4bits (or 2 symbols). Additionally, the block processor 713 performs ablock interleaving process in symbol units on the symbol-coded data.Subsequently, the block processor 713 converts to bytes the data symbolsthat are block-interleaved and have the order rearranged.

The group formatter 714 inserts the enhanced data outputted from theblock processor 713 (herein, the enhanced data may include supplementalinformation data such as signaling information including transmissioninformation) in a corresponding area within the data group, which isconfigured according to a pre-defined rule. Furthermore, in relationwith the data deinterleaving process, various types of places holders orknown data are also inserted in corresponding areas within the datagroup. At this point, the data group may be described by at least onehierarchical area. Herein, the data allocated to the each area may varydepending upon the characteristic of each hierarchical area.Additionally, each data group may be configured to include a fieldsynchronization signal.

In another example given in the present invention, a data group isdivided into A, B, and C regions in a data configuration prior to datadeinterleaving.

FIG. 13 illustrates an alignment of data before being data deinterleavedand identified, and FIG. 14 illustrates an alignment of data after beingdata deinterleaved and identified. More specifically, a data structureidentical to that shown in FIG. 13 is transmitted to a receiving system.Also, the data group configured to have the same structure as the datastructure shown in FIG. 13 is inputted to the data deinterleaver 715.

As described above, FIG. 13 illustrates a data structure prior to datadeinterleaving that is divided into 3 regions, such as region A, regionB, and region C. Also, in the present invention, each of the regions Ato C is further divided into a plurality of regions. Referring to FIG.13, region A is divided into 5 regions (A1 to A5), region B is dividedinto 2 regions (B1 and B2), and region C is divided into 3 regions (C1to C3). Herein, regions A to C are identified as regions having similarreceiving performances within the data group. Herein, the type ofenhanced data, which are inputted, may also vary depending upon thecharacteristic of each region.

In the example of the present invention, the data structure is dividedinto regions A to C based upon the level of interference of the maindata. Herein, the data group is divided into a plurality of regions tobe used for different purposes. More specifically, a region of the maindata having no interference or a very low interference level may beconsidered to have a more resistant (or stronger) receiving performanceas compared to regions having higher interference levels. Additionally,when using a system inserting and transmitting known data in the datagroup, and when consecutively long known data are to be periodicallyinserted in the enhanced data, the known data having a predeterminedlength may be periodically inserted in the region having no interferencefrom the main data (e.g., region A). However, due to interference fromthe main data, it is difficult to periodically insert known data andalso to insert consecutively long known data to a region havinginterference from the main data (e.g., region B and region C).

Hereinafter, examples of allocating data to region A (A1 to A5), regionB (B1 and B2), and region C (C1 to C3) will now be described in detailwith reference to FIG. 13. The data group size, the number ofhierarchically divided regions within the data group and the size ofeach region, and the number of enhanced data bytes that can be insertedin each hierarchically divided region of FIG. 13 are merely examplesgiven to facilitate the understanding of the present invention. Herein,the group formatter 714 creates a data group including places in whichfield synchronization bytes are to be inserted, so as to create the datagroup that will hereinafter be described in detail.

More specifically, region A is a region within the data group in which along known data sequence may be periodically inserted, and in whichincludes regions wherein the main data are not mixed (e.g., A1 to A5).Also, region A includes a region (e.g., A1) located between a fieldsynchronization region and the region in which the first known datasequence is to be inserted. The field synchronization region has thelength of one segment (i.e., 832 symbols) existing in an ATSC system.

For example, referring to FIG. 13, 2428 bytes of the enhanced data maybe inserted in region A1, 2580 bytes may be inserted in region A2, 2772bytes may be inserted in region A3, 2472 bytes may be inserted in regionA4, and 2772 bytes may be inserted in region A5. Herein, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the enhanced data. As described above, when region Aincludes a known data sequence at both ends, the receiving system useschannel information that can obtain known data or field synchronizationdata, so as to perform equalization, thereby providing enforcedequalization performance.

Also, region B includes a region located within 8 segments at thebeginning of a field synchronization region within the data group(chronologically placed before region A1) (e.g., region B1), and aregion located within B segments behind the very last known datasequence which is inserted in the data group (e.g., region B2). Forexample, 930 bytes of the enhanced data may be inserted in the regionB1, and 1350 bytes may be inserted in region B2. Similarly, trellisinitialization data or known data, MPEG header, and RS parity are notincluded in the enhanced data. In case of region B, the receiving systemmay perform equalization by using channel information obtained from thefield synchronization section. Alternatively, the receiving system mayalso perform equalization by using channel information that may beobtained from the last known data sequence, thereby enabling the systemto respond to the channel changes.

Region C includes a region located within 30 segments including andpreceding the 9^(th) segment of the field synchronization region(chronologically located before region A) (e.g., region C1), a regionlocated within 12 segments including and following the 9^(th) segment ofthe very last known data sequence within the data group (chronologicallylocated after region A) (e.g., region C2), and a region located in 32segments after the region C2 (e.g., region C3). For example, 1272 bytesof the enhanced data may be inserted in the region C1, 1560 bytes may beinserted in region C2, and 1312 bytes may be inserted in region C3.Similarly, trellis initialization data or known data, MPEG header, andRS parity are not included in the enhanced data. Herein, region C (e.g.,region C1) is located chronologically earlier than (or before) region A.

Since region C (e.g., region C1) is located further apart from the fieldsynchronization region which corresponds to the closest known dataregion, the receiving system may use the channel information obtainedfrom the field synchronization data when performing channelequalization. Alternatively, the receiving system may also use the mostrecent channel information of a previous data group. Furthermore, inregion C (e.g., region C2 and region C3) located before region A, thereceiving system may use the channel information obtained from the lastknown data sequence to perform equalization. However, when the channelsare subject to fast and frequent changes, the equalization may not beperformed perfectly. Therefore, the equalization performance of region Cmay be deteriorated as compared to that of region B.

When it is assumed that the data group is allocated with a plurality ofhierarchically divided regions, as described above, the block processor713 may encode the enhanced data, which are to be inserted to eachregion based upon the characteristic of each hierarchical region, at adifferent coding rate. For example, the block processor 713 may encodethe enhanced data, which are to be inserted in regions A1 to A5 ofregion A, at a coding rate of 1/2. Then, the group formatter 714 mayinsert the 1/2-rate encoded enhanced data to regions A1 to A5.

The block processor 713 may encode the enhanced data, which are to beinserted in regions B1 and B2 of region B, at a coding rate of 1/4having higher error correction ability as compared to the 1/2-codingrate. Then, the group formatter 714 inserts the 1/4-rate coded enhanceddata in region B1 and region B2. Furthermore, the block processor 713may encode the enhanced data, which are to be inserted in regions C1 toC3 of region C, at a coding rate of 1/4 or a coding rate having highererror correction ability than the 1/4-coding rate. Then, the groupformatter 714 may either insert the encoded enhanced data to regions C1to C3, as described above, or leave the data in a reserved region forfuture usage.

In addition, the group formatter 714 also inserts supplemental data,such as signaling information that notifies the overall transmissioninformation, other than the enhanced data in the data group. Also, apartfrom the encoded enhanced data outputted from the block processor 713,the group formatter 714 also inserts MPBG header place holders,non-systematic RS parity place holders, main data place holders, whichare related to data deinterleaving in a later process, as shown in FIG.13. Herein, the main data place holders are inserted because theenhanced data bytes and the main data bytes are alternately mixed withone another in regions B and C based upon the input of the datadeinterleaver, as shown in FIG. 13. For example, based upon the dataoutputted after data deinterleaving, the place holder for the MPEGheader may be allocated at the very beginning of each packet.

Furthermore, the group formatter 714 either inserts known data generatedin accordance with a pre-determined method or inserts known data placeholders for inserting the known data in a later process. Additionally,place holders for initializing the trellis encoder 727 are also insertedin the corresponding regions. For example, the initialization data placeholders may be inserted in the beginning of the known data sequence.Herein, the size of the enhanced data that can be inserted in a datagroup may vary in accordance with the sizes of the trellisinitialization place holders or known data (or known data placeholders), MPEG header place holders, and RS parity place holders.

The output of the group formatter 714 is inputted to the datadeinterleaver 715. And, the data deinterleaver 715 deinterleaves data byperforming an inverse process of the data interleaver on the data andplace holders within the data group, which are then outputted to thepacket formatter 716. More specifically, when the data and place holderswithin the data group configured, as shown in FIG. 13, are deinterleavedby the data deinterleaver 715, the data group being outputted to thepacket formatter 716 is configured to have the structure shown in FIG.14.

Among the data deinterleaved and inputted, the packet formatter 716removes the main data place holder and RS parity place holder that wereallocated for the deinterleaving process from the inputted deinterleaveddata. Thereafter, the remaining portion of the corresponding data isgrouped, and 4 bytes of MPEG header are inserted therein. The 4-byteMPEG header is configured of a 1-byte MPEG synchronization byte added tothe 3-byte MPEG header place holder.

When the group formatter 714 inserts the known data place holder, thepacket formatter 716 may either insert actual known data in the knowndata place holder or output the known data place holder without anychange or modification for a replacement insertion in a later process.Afterwards, the packet formatter 716 divides the data within theabove-described packet-formatted data group into 188-byte unit enhanceddata packets (i.e., MPEG TS packets), which are then provided to thepacket multiplexer 721. The packet multiplexer 721 multiplexes the188-byte unit enhanced data packet and main data packet outputted fromthe packet formatter 716 according to a pre-defined multiplexing method.Subsequently, the multiplexed data packets are outputted to the datarandomizer 722. The multiplexing method may be modified or altered inaccordance with diverse variables of the system design.

As an example of the multiplexing method of the packet multiplexer 721,the enhanced data burst section and the main data section may beidentified along a time axis (or a chronological axis) and may bealternately repeated. At this point, the enhanced data burst section maytransmit at least one data group, and the main data section may transmitonly the main data. The enhanced data burst section may also transmitthe main data. If the enhanced data are outputted in a burst structure,as described above, the receiving system receiving only the enhanceddata may turn the power on only during the burst section so as toreceive the enhanced data, and may turn the power off during the maindata section in which main data are transmitted, so as to prevent themain data from being received, thereby reducing the power consumption ofthe receiving system.

When the data being inputted correspond to the main data packet, thedata randomizer 722 performs the same randomizing process of theconventional randomizer. More specifically, the MPEG synchronizationbyte included in the main data packet is discarded and a pseudo randombyte generated from the remaining 187 bytes is used so as to randomizethe data. Thereafter, the randomized data are outputted to the RSencoder/non-systematic R5 encoder 723. However, when the inputted datacorrespond to the enhanced data packet, the MPEG synchronization byte ofthe 4-byte MPEG header included in the enhanced data packet isdiscarded, and data randomizing is performed only on the remaining3-byte MPEG header. Randomizing is not performed on the remainingportion of the enhanced data. Instead, the remaining portion of theenhanced data is outputted to the RS encoder/non-systematic RS encoder723. This is because the randomizing process has already been performedon the enhanced data by the enhanced data randomizer 711 in an earlierprocess. Herein, a data randomizing process may or may not be performedon the known data (or known data place holder) and the initializationdata place holder included in the enhanced data packet.

The RS encoder/non-systematic RS encoder 723 RS-codes the datarandomized by the data randomizer 722 or the data bypassing the datarandomizer 722. Then, the RS encoder/non-systematic RS encoder 723 addsa 20-byte RS parity to the coded data, thereby outputting theRS-parity-added data to the data interleaver 724. At this point, if theinputted data correspond to the main data packet, the RSencoder/non-systematic RS encoder 723 performs a systematic RS-codingprocess identical to that of the conventional receiving system on theinputted data, thereby adding the 20-byte RS parity at the end of the187-byte data. Alternatively, if the inputted data correspond to theenhanced data packet, the 20 bytes of RS parity gained by performing thenon-systematic RS-coding are respectively inserted in the decided paritybyte places within the enhanced data packet. Herein, the datainterleaver 724 corresponds to a byte unit convolutional interleaver.The output of the data interleaver 724 is inputted to the parity bytereplacer 725 and the non-systematic RS encoder 726.

Meanwhile, a memory within the trellis encoding module 727, which ispositioned after the parity byte replacer 725, should first beinitialized in order to allow the output data of the trellis encodingmodule 727 so as to become the known data defined based upon anagreement between the receiving system and the transmitting system. Morespecifically, the memory of the trellis encoding module 727 should firstbe initialized before the known data sequence being inputted istrellis-encoded. At this point, the beginning of the known data sequencethat is inputted corresponds to the initialization data place holderinserted by the group formatter 714 and not the actual known data.Therefore, a process of generating initialization data right before thetrellis-encoding of the known data sequence being inputted and a processof replacing the initialization data place holder of the correspondingtrellis encoding module memory with the newly generated initializationdata are required.

A value of the trellis memory initialization data is decided based uponthe memory status of the trellis encoding module 727, thereby generatingthe trellis memory initialization data accordingly. Due to the influenceof the replace initialization data, a process of recalculating the RSparity, thereby replacing the RS parity outputted from the trellisencoding module 727 with the newly calculated RS parity is required.Accordingly, the non-systematic RS encoder 726 receives the enhanceddata packet including the initialization data place holder that is to bereplaced with the initialization data from the data interleaver 724 andalso receives the initialization data from the trellis encoding module727. Thereafter, among the received enhanced data packet, theinitialization data place holder is replaced with the initializationdata. Subsequently, the RS parity data added to the enhanced data packetare removed. Then, a new non-systematic RS parity is calculated andoutputted to the parity byte replacer 725. Accordingly, the parity bytereplacer 725 selects the output of the data interleaver 724 as the datawithin the enhanced data packet, and selects the output of thenon-systematic RS encoder 726 as the RS parity. Thereafter, the paritybyte replacer 725 outputs the selected data.

Meanwhile, if the main data packet is inputted, or if the enhanced datapacket that does not include the initialization data place holder thatis to be replaced, the parity byte replacer 725 selects the data and RSparity outputted from the data interleaver 724 and directly outputs theselected data to the trellis encoding module 727 without modification.The trellis encoding module 727 converts the byte-unit data tosymbol-unit data and 12-way interleaves and trellis-encodes theconverted data, which are then outputted to the frame multiplexer 728.The frame multiplexer 728 inserts field synchronization and segmentsynchronization signals in the output of the trellis encoding module 727and then outputs the processed data to the transmitting unit 730.Herein, the transmitting unit 730 includes a pilot inserter 731, amodulator 732, and a radio frequency (RF) up-converter 733. Theoperation of the transmitting unit 730 is identical to the conventionaltransmitters. Therefore, a detailed description of the same will beomitted for simplicity.

FIG. 15 illustrates a block diagram of a demodulating unit included inthe receiving system according to another embodiment of the presentinvention. Herein, the demodulating unit may effectively process signalstransmitted from the transmitting system shown in FIG. 12. Referring toFIG. 15, the demodulating unit includes a demodulator 801, a channelequalizer 802, a known data detector 803, a block decoder 804, anenhanced data deformatter 805, a RS frame decoder B06, an enhanced dataderandomizer 807, a data deinterleaver 808, a RS decoder 809, and a maindata derandomizer 810. For simplicity, the demodulator 801, the channelequalizer 802, the known data detector 803, the block decoder 804, theenhanced data deformatter 805, the RS frame decoder 806, and theenhanced data derandomizer 807 will be referred to as an enhanced dataprocessor. And, the data deinterleaver 808, the RS decoder 809, and themain data derandomizer 810 will be referred to as a main data processor.

More specifically, the enhanced data including known data and the maindata are received through the tuner and inputted to the demodulator 801and the known data detector 803. The demodulator 801 performs automaticgain control, carrier wave recovery, and timing recovery on the datathat are being inputted, thereby creating baseband data, which are thenoutputted to the equalizer 802 and the known data detector 803. Theequalizer 802 compensates the distortion within the channel included inthe demodulated data. Then, the equalizer 802 outputs the compensateddata to the block decoder B04.

At this point, the known data detector 803 detects the known data placeinserted by the transmitting system to the input/output data of thedemodulator 801 (i.e., data prior to demodulation or data afterdemodulation). Then, along with the position information, the known datadetector 803 outputs the symbol sequence of the known data generatedfrom the corresponding position to the demodulator 801 and the equalizer802. Additionally, the known data detector 803 outputs informationenabling the block decoder 804 to identify the enhanced data beingadditionally encoded by the transmitting system and the main data thatare not additionally encoded to the block decoder 804. Furthermore,although the connection is not shown in FIG. 15, the informationdetected by the known data detector 803 may be used in the overallreceiving system and may also be used in the enhanced data formatter 805and the RS frame decoder 806.

By using the known data symbol sequence when performing the timingrecovery or carrier wave recovery, the demodulating performance of thedemodulator 801 may be enhanced. Similarly, by using the known data, thechannel equalizing performance of the channel equalizer 802 may beenhanced. Furthermore, by feeding-back the decoding result of the blockdecoder 804 to the channel equalizer 802, the channel equalizingperformance may also be enhanced.

The channel equalizer 802 may perform channel equalization by using aplurality of methods. An example of estimating a channel impulseresponse (CIR) so as to perform channel equalization will be given inthe description of the present invention. Most particularly, an exampleof estimating the CIR in accordance with each region within the datagroup, which is hierarchically divided and transmitted from thetransmitting system, and applying each CIR differently will also bedescribed herein. Furthermore, by using the known data, the place andcontents of which is known in accordance with an agreement between thetransmitting system and the receiving system, and the fieldsynchronization data, so as to estimate the CIR, the present inventionmay be able to perform channel equalization with more stability.

Herein, the data group that is inputted for the equalization process isdivided into regions A to C, as shown in FIG. 13. More specifically, inthe example of the present invention, each region A, B, and C arefurther divided into regions A1 to A5, regions B1 and B2, and regions C1to C3, respectively. Referring to FIG. 13, the CIR that is estimatedfrom the field synchronization data in the data structure is referred toas CIR_FS. Alternatively, the CIRs that are estimated from each of the 5known data sequences existing in region A are sequentially referred toas CIR_N0, CIR_N1, CIR_N2, CIR_N3, and CIR_N4.

As described above, the present invention uses the CIR estimated fromthe field synchronization data and the known data sequences in order toperform channel equalization on data within the data group. At thispoint, each of the estimated CIRs may be directly used in accordancewith the characteristics of each region within the data group.Alternatively, a plurality of the estimated CIRs may also be eitherinterpolated or extrapolated so as to create a new CIR, which is thenused for the channel equalization process.

Herein, when a value F(Q) of a function F(x) at a particular point Q anda value F(S) of the function F(x) at another particular point S areknown, interpolation refers to estimating a function value of a pointwithin the section between points Q and S. Linear interpolationcorresponds to the simplest form among a wide range of interpolationoperations. The linear interpolation described herein is merelyexemplary among a wide range of possible interpolation methods. And,therefore, the present invention is not limited only to the examples setforth herein.

Alternatively, when a value F(Q) of a function F(x) at a particularpoint Q and a value F(S) of the function F(x) at another particularpoint S are known, extrapolation refers to estimating a function valueof a point outside of the section between points Q and S. Linearextrapolation is the simplest form among a wide range of extrapolationoperations. Similarly, the linear extrapolation described herein ismerely exemplary among a wide range of possible extrapolation methods.And, therefore, the present invention is not limited only to theexamples set forth herein.

More specifically, in case of region C1, any one of the CIR_N4 estimatedfrom a previous data group, the CIR_FS estimated from the current datagroup that is to be processed with channel equalization, and a new CIRgenerated by extrapolating the CIR_FS of the current data group and theCIR_N0 may be used to perform channel equalization. Alternatively, incase of region B1, a variety of methods may be applied as described inthe case for region C1. For example, a new CIR created by linearlyextrapolating the CIR_FS estimated from the current data group and theCIR_N0 may be used to perform channel equalization. Also, the CIR_FSestimated from the current data group may also be used to performchannel equalization. Finally, in case of region A1, a new CIR may becreated by interpolating the CIR_FS estimated from the current datagroup and CIR_N0, which is then used to perform channel equalization.Furthermore, any one of the CIR_FS estimated from the current data groupand CIR_N0 may be used to perform channel equalization.

In case of regions A2 to A5, CIR_N(i−1) estimated from the current datagroup and CIR_N(i) may be interpolated to create a new CIR and use thenewly created CIR to perform channel equalization. Also, any one of theCIR_N(i−1) estimated from the current data group and the CIR_N(i) may beused to perform channel equalization. Alternatively, in case of regionsB2, C2, and C3, CIR_N3 and CIR_N4 both estimated from the current datagroup may be extrapolated to create a new CIR, which is then used toperform the channel equalization process. Furthermore, the CIR_N4estimated from the current data group may be used to perform the channelequalization process. Accordingly, an optimum performance may beobtained when performing channel equalization on the data inserted inthe data group. The methods of obtaining the CIRs required forperforming the channel equalization process in each region within thedata group, as described above, are merely examples given to facilitatethe understanding of the present invention. A wider range of methods mayalso be used herein. And, therefore, the present invention will not onlybe limited to the examples given in the description set forth herein.

Meanwhile, if the data being channel equalized and then inputted to theblock decoder B04 correspond to the enhanced data on which additionalencoding and trellis encoding are both performed by the transmittingsystem, trellis-decoding and additional decoding processes are performedas inverse processes of the transmitting system. Alternatively, if thedata being channel equalized and then inputted to the block decoder 804correspond to the main data on which additional encoding is notperformed and only trellis-encoding is performed by the transmittingsystem, only the trellis-decoding process is performed. The data groupdecoded by the block decoder 804 is inputted to the enhanced datadeformatter 805, and the main data packet is inputted to the datadeinterleaver 808.

More specifically, if the inputted data correspond to the main data, theblock decoder 804 performs Viterbi decoding on the inputted data, so asto either output a hard decision value or hard-decide a soft decisionvalue and output the hard-decided result. On the other hand, if theinputted correspond to the enhanced data, the block decoder 804 outputseither a hard decision value or a soft decision value on the inputtedenhanced data. In other words, if the data inputted to the block decoder804 correspond to the enhanced data, the block decoder 804 performs adecoding process on the data encoded by the block processor and thetrellis encoder of the transmitting system. At this point, the output ofthe RS frame encoder included in the pre-processor of the transmittingsystem becomes an external code, and the output of the block processorand the trellis encoder becomes an internal code. In order to showmaximum performance of the external code when decoding such connectioncodes, the decoder of the internal code should output a soft decisionvalue. Therefore, the block decoder 804 may output a hard decision valueon the enhanced data. However, when required, it is more preferable thatthe block decoder 804 outputs a soft decision value.

The present invention may also be used for configuring a reliability mapusing the soft decision value. The reliability map determines andindicates whether a byte corresponding to a group of 8 bits decided bythe code of the soft decision value is reliable. For example, when anabsolute value of the soft decision value exceeds a pre-determinedthreshold value, the value of the bit corresponding to the soft decisionvalue code is determined to be reliable. However, if the absolute valuedoes not exceed the pre-determined threshold value, then the value ofthe corresponding bit is determined to be not reliable. Further, if atleast one bit among the group of 8 bits, which are determined based uponthe soft decision value, is determined to be not reliable, then thereliability map indicates that the entire byte is not reliable. Herein,the process of determining the reliability by 1-bit units is merelyexemplary. The corresponding byte may also be indicated to be notreliable if a plurality of bits (e.g., 4 bits) is determined to be notreliable.

Conversely, when all of the bits are determined to be reliable withinone byte (i.e., when the absolute value of the soft value of all bitsexceeds the pre-determined threshold value), then the reliability mapdetermines and indicates that the corresponding data byte is reliable.Similarly, when more than 4 bits are determined to be reliable withinone data byte, then the reliability map determines and indicates thatthe corresponding data byte is reliable. The estimated numbers aremerely exemplary and do not limit the scope and spirit of the presentinvention. Herein, the reliability map may be used when performing errorcorrection decoding processes.

Meanwhile, the data deinterleaver 808, the RS decoder 809, and the maindata derandomizer 810 are blocks required for receiving the main data.These blocks may not be required in a receiving system structure thatreceives only the enhanced data. The data deinterleaver 808 performs aninverse process of the data interleaver of the transmitting system. Morespecifically, the data deinterleaver 808 deinterleaves the main databeing outputted from the block decode 804 and outputs the deinterleaveddata to the RS decoder 809. The RS decoder 809 performs systematic RSdecoding on the deinterleaved data and outputs the systematicallydecoded data to the main data derandomizer 810. The main dataderandomizer 810 receives the data outputted from the RS decoder 809 soas to generate the same pseudo random byte as that of the randomizer inthe transmitting system. The main data derandomizer 810 then performs abitwise exclusive OR (XOR) operation on the generated pseudo random databyte, thereby inserting the MPEG synchronization bytes to the beginningof each packet so as to output the data in 188-byte main data packetunits.

Herein, the format of the data being outputted to the enhanced datadeformatter 805 from the block decoder 804 is a data group format. Atthis point, the enhanced data deformatter 805 already knows thestructure of the input data. Therefore, the enhanced data deformatter805 identifies the system information including signaling informationand the enhanced data from the data group. Thereafter, the identifiedsignaling information is transmitted to where the system information isrequired, and the enhanced data are outputted to the RS frame decoder806. The enhanced data deformatter 805 removes the known data, trellisinitialization data, and MPEG header that were included in the main dataand the data group and also removes the RS parity that was added by theRS encoder/non-systematic RS encoder of the transmitting system.Thereafter, the processed data are outputted to the RS frame decoder806.

More specifically, the RS frame decoder 806 receives the RS-coded andCRC-coded enhanced data from the enhanced data deformatter 805 so as toconfigure the RS frame. The RS frame decoder 806 performs an inverseprocess of the RS frame encoder included in the transmitting system,thereby correcting the errors within the RS frame. Then, the 1-byte MPEGsynchronization byte, which was removed during the RS frame codingprocess, is added to the error corrected enhanced data packet.Subsequently, the processed data are outputted to the enhanced dataderandomizer 807. Herein, the enhanced data derandomizer 807 performs aderandomizing process, which corresponds to an inverse process of theenhanced data randomizer included in the transmitting system, on thereceived enhanced data. Then, by outputting the processed data, theenhanced data transmitted from the transmitting system can be obtained.

According to an embodiment of the present invention, the RS framedecoder 806 may also be configured as follows. The RS frame decoder 806may perform a CRC syndrome check on the RS frame, thereby verifyingwhether or not an error has occurred in each row. Subsequently, the CRCchecksum is removed and the presence of an error is indicated on a CRCerror flag corresponding to each row. Then, a RS decoding process isperformed on the RS frame having the CRC checksum removed in a columndirection. At this point, depending upon the number of CRC error flags,a RS erasure decoding process may be performed. More specifically, bychecking the CRC error flags corresponding to each row within the RSframe, the number of CRC error flags may be determined whether it isgreater or smaller than the maximum number of errors, when RS decodingthe number of rows with errors (or erroneous rows) in the columndirection. Herein, the maximum number of errors corresponds to thenumber of parity bytes inserted during the RS decoding process. As anexample of the present invention, it is assumed that 48 parity bytes areadded to each column.

If the number of rows with CRC errors is equal to or smaller than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process is performedon the RS frame in the column direction. Thereafter, the 48 bytes ofparity data that were added at the end of each column are removed.However, if the number of rows with CRC errors is greater than themaximum number of errors (e.g., 48), which may be corrected by the RSerasure decoding process, the RS erasure decoding process cannot beperformed. In this case, the error may be corrected by performing ageneral RS decoding process.

As another embodiment of the present invention, the error correctionability may be enhanced by using the reliability map created whenconfiguring the RS frame from the soft decision value. Morespecifically, the RS frame decoder 806 compares the absolute value ofthe soft decision value obtained from the block decoder 804 to thepre-determined threshold value so as to determine the reliability of thebit values that are decided by the code of the corresponding softdecision value. Then, 8 bits are grouped to configure a byte. Then, thereliability information of the corresponding byte is indicated on thereliability map. Therefore, even if a specific row is determined to haveCRC errors as a result of the CRC syndrome checking process of thecorresponding row, it is not assumed that all of the data bytes includedin the corresponding row have error. Instead, only the data bytes thatare determined to be not reliable, after referring to the reliabilityinformation on the reliability map, are set to have errors. In otherwords, regardless of the presence of CRC errors in the correspondingrow, only the data bytes that are determined to be not reliable (orunreliable) by the reliability map are set as erasure points.

Thereafter, if the number of erasure points for each column is equal toor smaller than the maximum number of errors (e.g., 48), the RS erasuredecoding process is performed on the corresponding the column.Conversely, if the number of erasure points is greater than the maximumnumber of errors (e.g., 48), which may be corrected by the RS erasuredecoding process, a general decoding process is performed on thecorresponding column. In other words, if the number of rows having CRCerrors is greater than the maximum number of errors (e.g., 48), whichmay be corrected by the RS erasure decoding process, either a RS erasuredecoding process or a general RS decoding process is performed on aparticular column in accordance with the number of erasure point withinthe corresponding column, wherein the number is decided based upon thereliability information on the reliability map. When the above-describedprocess is performed, the error correction decoding process is performedin the direction of all of the columns included in the RS frame.Thereafter, the 48 bytes of parity data added to the end of each columnare removed.

FIG. 16 illustrates a block diagram showing the structure of a digitalbroadcast receiving system according to an embodiment of the presentinvention. Referring to FIG. 16, the digital broadcast receiving systemincludes a tuner 901, a demodulating unit 902, a demultiplexer 903, anaudio decoder 904, a video decoder 905, a native TV application manager906, a channel manager 907, a channel map 908, a first memory 909, adata decoder 910, a second memory 911, a system manager 912, a databroadcasting application manager 913, a storage controller 914, and athird memory 915. Herein, the third memory 915 is a mass storage device,such as a hard disk drive (HDD) or a memory chip. The tuner 901 tunes afrequency of a specific channel through any one of an antenna, cable,and satellite. Then, the tuner 901 down-converts the tuned frequency toan intermediate frequency (IF), which is then outputted to thedemodulating unit 902. At this point, the tuner 901 is controlled by thechannel manager 907. Additionally, the result and strength of thebroadcast signal of the tuned channel are also reported to the channelmanager 907. The data that are being received by the frequency of thetuned specific channel include main data, enhanced data, and table datafor decoding the main data and enhanced data.

In the embodiment of the present invention, examples of the enhanceddata may include data provided for data service, such as Javaapplication data, HTML application data, XML data, and so on. The dataprovided for such data services may correspond either to a Java classfile for the Java application, or to a directory file designatingpositions (or locations) of such files. Furthermore, such data may alsocorrespond to an audio file and/or a video file used in eachapplication. The data services may include weather forecast services,traffic information services, stock information services, servicesproviding information quiz programs providing audience participationservices, real time poll, user interactive education programs, gamingservices, services providing information on soap opera (or TV series)synopsis, characters, original sound track, filing sites, servicesproviding information on past sports matches, profiles andaccomplishments of sports players, product information and productordering services, services providing information on broadcast programsby media type, airing time, subject, and so on. The types of dataservices described above are only exemplary and are not limited only tothe examples given herein. Furthermore, depending upon the embodiment ofthe present invention, the enhanced data may correspond to meta data.For example, the meta data use the XML application so as to betransmitted through a DSM-CC protocol.

The demodulating unit 902 performs demodulation and channel equalizationon the signal being outputted from the tuner 901, thereby identifyingthe main data and the enhanced data. Thereafter, the identified maindata and enhanced data are outputted in TS packet units. Examples of thedemodulating unit 902 are shown in FIG. 11 and FIG. 15. The demodulatingunit shown in FIG. 11 and FIG. 15 is merely exemplary and the scope ofthe present invention is not limited to the examples set forth herein.In the embodiment given as an example of the present invention, only theenhanced data packet outputted from the demodulating unit 902 isinputted to the demultiplexer 903. In this case, the main data packet isinputted to another demultiplexer (not shown) that processes main datapackets. Herein, the storage controller 914 is also connected to theother demultiplexer in order to store the main data after processing themain data packets. The demultiplexer of the present invention may alsobe designed to process both enhanced data packets and main data packetsin a single demultiplexer.

The storage controller 914 is interfaced with the demultipelxer so as tocontrol instant recording, reserved (or pre-programmed) recording, timeshift, and so on of the enhanced data and/or main data. For example,when one of instant recording, reserved (or pre-programmed) recording,and time shift is set and programmed in the receiving system (orreceiver) shown in FIG. 16, the corresponding enhanced data and/or maindata that are inputted to the demultiplexer are stored in the thirdmemory 915 in accordance with the control of the storage controller 914.The third memory 915 may be described as a temporary storage area and/ora permanent storage area. Herein, the temporary storage area is used forthe time shifting function, and the permanent storage area is used for apermanent storage of data according to the user's choice (or decision).

When the data stored in the third memory 915 need to be reproduced (orplayed), the storage controller 914 reads the corresponding data storedin the third memory 915 and outputs the read data to the correspondingdemultiplexer (e.g., the enhanced data are outputted to thedemultiplexer 903 shown in FIG. 16). At this point, according to theembodiment of the present invention, since the storage capacity of thethird memory 915 is limited, the compression encoded enhanced dataand/or main data that are being inputted are directly stored in thethird memory 915 without any modification for the efficiency of thestorage capacity. In this case, depending upon the reproduction (orreading) command, the data read from the third memory 915 pass troughthe demultiplexer so as to be inputted to the corresponding decoder,thereby being restored to the initial state.

The storage controller 914 may control the reproduction (or play),fast-forward, rewind, slow motion, instant replay functions of the datathat are already stored in the third memory 915 or presently beingbuffered. Herein, the instant replay function corresponds to repeatedlyviewing scenes that the viewer (or user) wishes to view once again. Theinstant replay function may be performed on stored data and also on datathat are currently being received in real time by associating theinstant replay function with the time shift function. If the data beinginputted correspond to the analog format, for example, if thetransmission mode is NTSC, PAL, and so on, the storage controller 914compression encodes the inputted data and stored the compression-encodeddata to the third memory 915. In order to do so, the storage controller914 may include an encoder, wherein the encoder may be embodied as oneof software, middleware, and hardware. Herein, an MPEG encoder may beused as the encoder according to an embodiment of the present invention.The encoder may also be provided outside of the storage controller 914.

Meanwhile, in order to prevent illegal duplication (or copies) of theinput data being stored in the third memory 915, the storage controller914 scrambles the input data and stores the scrambled data in the thirdmemory 915. Accordingly, the storage controller 914 may include ascramble algorithm for scrambling the data stored in the third memory915 and a descramble algorithm for descrambling the data read from thethird memory 915. Herein, the definition of scramble includesencryption, and the definition of descramble includes decryption. Thescramble method may include using an arbitrary key (e.g., control word)to modify a desired set of data, and also a method of mixing signals.

Meanwhile, the demultiplexer 903 receives the real-time data outputtedfrom the demodulating unit 902 or the data read from the third memory915 and demultiplexes the received data. In the example given in thepresent invention, the demultiplexer 903 performs demultiplexing on theenhanced data packet. Therefore, in the present invention, the receivingand processing of the enhanced data will be described in detail. Itshould also be noted that a detailed description of the processing ofthe main data will be omitted for simplicity starting from thedescription of the demultiplexer 903 and the subsequent elements.

The demultiplexer 903 demultiplexer enhanced data and program specificinformation/program and system information protocol (PSI/PSIP) tablesfrom the enhanced data packet inputted in accordance with the control ofthe data decoder 910. Thereafter, the demultiplexed enhanced data andPSI/PSIP tables are outputted to the data decoder 910 in a sectionformat. In order to extract the enhanced data from the channel throughwhich enhanced data are transmitted and to decode the extracted enhanceddata, system information is required. Such system information may alsobe referred to as service information. The system information mayinclude channel information, event information, etc. In the embodimentof the present invention, the PSI/PSIP tables are applied as the systeminformation. However, the present invention is not limited to theexample set forth herein. More specifically, regardless of the name, anyprotocol transmitting system information in a table format may beapplied in the present invention.

The PSI table is an MPEG-2 system standard defined for identifying thechannels and the programs. The PSIP table is an advanced televisionsystems committee (ATSC) standard that can identify the channels and theprograms. The PSI table may include a program association table (PAT), aconditional access table (CAT), a program map table (PMT), and a networkinformation table (NIT). Herein, the PAT corresponds to specialinformation that is transmitted by a data packet having a PID of ‘0’.The PAT transmits PID information of the PMT and PID information of theNIT corresponding to each program. The CAT transmits information on apaid broadcast system used by the transmitting system. The PMT transmitsPID information of a transport stream (TS) packet, in which programidentification numbers and individual bit sequences of video and audiodata configuring the corresponding program are transmitted, and the PIDinformation, in which PCR is transmitted. The NIT transmits informationof the actual transmission network.

The PSIP table may include a virtual channel table (VCT), a system timetable (STT), a rating region table (RRT), an extended text table (ETT),a direct channel change table (DCCT), an event information table (EIT),and a master guide table (MGT). The VCT transmits information on virtualchannels, such as channel information for selecting channels andinformation such as packet identification (PID) numbers for receivingthe audio and/or video data. More specifically, when the VCT is parsed,the PID of the audio/video data of the broadcast program may be known.Herein, the corresponding audio/video data are transmitted within thechannel along with the channel name and the channel number. The STTtransmits information on the current data and timing information. TheRRT transmits information on region and consultation organs for programratings. The EIT transmits additional description of a specific channeland broadcast program. The EIT transmits information on virtual channelevents (e.g., program title, program start time, etc.). The DCCT/DCCSCTtransmits information associated with automatic (or direct) channelchange. And, the MGT transmits the versions and PID information of theabove-mentioned tables included in the PSIP.

Each of the above-described tables included in the PSI/PSIP isconfigured of a basic unit referred to as a “section”, and a combinationof one or more sections forms a table. For example, the VCT may bedivided into 256 sections. Herein, one section may include a pluralityof virtual channel information. However, a single set of virtual channelinformation is not divided into two or more sections. At this point, thereceiving system may parse and decode the data for the data service thatare transmitting by using only the tables included in the PSI, or onlythe tables included in the PISP, or a combination of tables included inboth the PSI and the PSIP. In order to parse and decode the data for thedata service, at least one of the PAT and PMT included in the PSI, andthe VCT included in the PSIP is required. For example, the PAT mayinclude the system information for transmitting the data correspondingto the data service, and the PID of the PMT corresponding to the dataservice data (or program number). The PMT may include the PID of the TSpacket used for transmitting the data service data. The VCT may includeinformation on the virtual channel for transmitting the data servicedata, and the PID of the TS packet for transmitting the data servicedata.

Meanwhile, depending upon the embodiment of the present invention, aDVB-SI may be applied instead of the PSIP. The DVB-SI may include anetwork information table (NIT), a service description table (SDT), anevent information table (EIT), and a time and data table (TDT). TheDVB-SI may be used in combination with the above-described PSI. Herein,the NIT divides the services corresponding to particular networkproviders by specific groups. The NIT includes all tuning informationthat are used during the IRD set-up, The NIT may be used for informingor notifying any change in the tuning information. The SDT includes theservice name and different parameters associated with each servicecorresponding to a particular MPEG multiplex. The EIT is used fortransmitting information associated with all events occurring in theMPEG multiplex. The EIT includes information on the current transmissionand also includes information selectively containing differenttransmission streams that may be received by the IRD. And, the TDT isused for updating the clock included in the IRD.

Furthermore, three selective SI tables (i.e., a bouquet associate table(BAT), a running status table (RST), and a stuffing table (ST)) may alsobe included. More specifically, the bouquet associate table (BAT)provides a service grouping method enabling the IRD to provide servicesto the viewers. Each specific service may belong to at least one‘bouquet’ unit. A running status table (RST) section is used forpromptly and instantly updating at least one event execution status. Theexecution status section is transmitted only once at the changing pointof the event status. Other SI tables are generally transmitted severaltimes. The stuffing table (ST) may be used for replacing or discarding asubsidiary table or the entire SI tables.

In the present invention, the enhanced data included in the payloadwithin the TS packet consist of a digital storage media-command andcontrol (DSM-CC) section format. However, the TS packet including thedata service data may correspond either to a packetized elementarystream (PES) type or to a section type. More specifically, either thePES type data service data configure the TS packet, or the section typedata service data configure the TS packet. The TS packet configured ofthe section type data will be given as the example of the presentinvention. At this point, the data service data are includes in thedigital storage media-command and control (DSM-CC) section. Herein, theDSM-CC section is then configured of a 188-byte unit TS packet.

Furthermore, the packet identification of the TS packet configuring theDSM-CC section is included in a data service table (DST). Whentransmitting the DST, ‘0x95’ is assigned as the value of a stream_typefield included in the service location descriptor of the PMT or the VCT.More specifically, when the PMT or VCT stream_type field value is‘0x95’, the receiving system may acknowledge that data broadcastingincluding enhanced data (i.e., the enhanced data) is being received. Atthis point, the enhanced data may be transmitted by a data carouselmethod. The data carousel method corresponds to repeatedly transmittingidentical data on a regular basis.

At this point, according to the control of the data decoder 910, thedemultiplexer 903 performs section filtering, thereby discardingrepetitive sections and outputting only the non-repetitive sections tothe data decoder 910. The demultiplexer 903 may also output only thesections configuring desired tables (e.g., VCT) to the data decoder 910by section filtering. Herein, the VCT may include a specific descriptorfor the enhanced data. However, the present invention does not excludethe possibilities of the enhanced data being included in other tables,such as the PMT. The section filtering method may include a method ofverifying the PID of a table defined by the MGT, such as the VCT, priorto performing the section filtering process. Alternatively, the sectionfiltering method may also include a method of directly performing thesection filtering process without verifying the MGT, when the VCTincludes a fixed PID (i.e., a base PID). At this point, thedemultiplexer 903 performs the section filtering process by referring toa table_id field, a version number field, a section_number field, etc.

As described above, the method of defining the PID of the VCT broadlyincludes two different methods. Herein, the PID of the VCT is a packetidentifier required for identifying the VCT from other tables. The firstmethod consists of setting the PID of the VCT so that it is dependent tothe MGT. In this case, the receiving system cannot directly verify theVCT among the many PSI and/or PSIP tables, Instead, the receiving systemmust check the PID defined in the MGT in order to read the VCT. Herein,the MGT defines the PID, size, version number, and so on, of diversetables. The second method consists of setting the PID of the VCT so thatthe PID is given a base PID value (or a fixed PID value), thereby beingindependent from the MGT. In this case, unlike in the first method, theVCT according to the present invention may be identified without havingto verify every single PID included in the MGT. Evidently, an agreementon the base PID must be previously made between the transmitting systemand the receiving system.

Meanwhile, in the embodiment of the present invention, the demultiplexer903 may output only an application information table (AIT) to the datadecoder 910 by section filtering. The AIT includes information on anapplication being operated in the receiving system for the data service.The AIT may also be referred to as an XAIT, and an AMT. Therefore, anytable including application information may correspond to the followingdescription. When the AIT is transmitted, a value of ‘0x05’ may beassigned to a stream_type field of the PMT. The AIT may includeapplication information, such as application name, application version,application priority, application ID, application status (i.e.,auto-start, user-specific settings, kill, etc.), application type (i.e.,Java or HTML), position (or location) of stream including applicationclass and data files, application platform directory, and location ofapplication icon.

In the method for detecting application information for the data serviceby using the AIT, component_tag, original_network_id,transport_stream_id, and service_id fields may be used for detecting theapplication information. The component_tag field designates anelementary stream carrying a DSI of a corresponding object carousel. Theoriginal_network_id field indicates a DVB-SI original_network_id of theTS providing transport connection. The transport_stream_id fieldindicates the MPEG TS of the TS providing transport connection, and theservice_id field indicates the DVB-SI of the service providing transportconnection. Information on a specific channel may be obtained by usingthe original_netwcrk_id field, the transport_stream_id field, and theservice_id field. The data service data, such as the application data,detected by using the above-described method may be stored in the secondmemory 911 by the data decoder 910.

The data decoder 910 parses the DSM-CC section configuring thedemultiplexed enhanced data. Then, the enhanced data corresponding tothe parsed result are stored as a database in the second memory 911. Thedata decoder 910 groups a plurality of sections having the same tableidentification (table_id) so as to configure a table, which is thenparsed. Thereafter, the parsed result is stored as a database in thesecond memory 911. At this point, by parsing data and/or sections, thedata decoder 910 reads all of the remaining actual section data that arenot section-filtered by the demultiplexer 903. Then, the data decoder910 stores the read data to the second memory 911. The second memory 911corresponds to a table and data carousel database storing systeminformation parsed from tables and enhanced data parsed from the DSM-CCsection. Herein, a table_id field, a section_number field, and alast_section_number field included in the table may be used to indicatewhether the corresponding table is configured of a single section or aplurality of sections. For example, TS packets having the PID of the VCTare grouped to form a section, and sections having table identifiersallocated to the VCT are grouped to form the VCT.

When the VCT is parsed, information on the virtual channel to whichenhanced data are transmitted may be obtained. The obtained applicationidentification information, service component identificationinformation, and service information corresponding to the data servicemay either be stored in the second memory 911 or be outputted to thedata broadcasting application manager 913. In addition, reference may bemade to the application identification information, service componentidentification information, and service information in order to decodethe data service data. Alternatively, such information may also preparethe operation of the application program for the data service.Furthermore, the data decoder 910 controls the demultiplexing of thesystem information table, which corresponds to the information tableassociated with the channel and events. Thereafter, an A.V PID list maybe transmitted to the channel manager 907.

The channel manager 907 may refer to the channel map 908 in order totransmit a request for receiving system-related information data to thedata decoder 910, thereby receiving the corresponding result. Inaddition, the channel manager 907 may also control the channel tuning ofthe tuner 901. Furthermore, the channel manager 907 may directly controlthe demultiplexer 943, so as to set up the A/V PID, thereby controllingthe audio decoder 904 and the video decoder 905. The audio decoder 904and the video decoder 905 may respectively decode and output the audiodata and video data demultiplexed from the main data packet.Alternatively, the audio decoder 904 and the video decoder 905 mayrespectively decode and output the audio data and video datademultiplexed from the enhanced data packet. Meanwhile, when theenhanced data include data service data, and also audio data and videodata, it is apparent that the audio data and video data demultiplexed bythe demultiplexer 903 are respectively decoded by the audio decoder 904and the video decoder 905. For example, an audio-coding (AC)-3 decodingalgorithm may be applied to the audio decoder 904, and a MPEG-2 decodingalgorithm may be applied to the video decoder 905.

Meanwhile, the native TV application manager 906 operates a nativeapplication program stored in the first memory 909, thereby performinggeneral functions such as channel change. The native application programrefers to software stored in the receiving system upon shipping of theproduct. More specifically, when a user request (or command) istransmitted to the receiving system through a user interface (UI), thenative TV application manger 906 displays the user request on a screenthrough a graphic user interface (GUI), thereby responding to the user'srequest. The user interface receives the user request through an inputdevice, such as a remote controller, a key pad, a jog controller, an atouch-screen provided on the screen, and then outputs the received userrequest to the native TV application manager 906 and the databroadcasting application manager 913. Furthermore, the native TVapplication manager 906 controls the channel manager 907, therebycontrolling channel-associated, such as the management of the channelmap 908, and controlling the data decoder 910. The native TV applicationmanager 906 also controls the GUI of the overall receiving system,thereby storing the user request and status of the receiving system inthe first memory 909 and restoring the stored information.

The channel manager 907 controls the tuner 901 and the data decoder 910,so as to managing the channel map 908 so that it can respond to thechannel request made by the user. More specifically, channel manager 907sends a request to the data decoder 910 so that the tables associatedwith the channels that are to be tuned are parsed. The results of theparsed tables are reported to the channel manager 907 by the datadecoder 910. Thereafter, based on the parsed results, the channelmanager 907 updates the channel map 908 and sets up a PID in thedemultiplexer 903 for demultiplexing the tables associated with the dataservice data from the enhanced data.

The system manager 912 controls the booting of the receiving system byturning the power on or off. Then, the system manager 912 stores ROMimages (including downloaded software images) in the first memory 909.More specifically, the first memory 909 stores management programs suchas operating system (OS) programs required for managing the receivingsystem and also application program executing data service functions.The application program is a program processing the data service datastored in the second memory 911 so as to provide the user with the dataservice. If the data service data are stored in the second memory 911,the corresponding data service data are processed by the above-describedapplication program or by other application programs, thereby beingprovided to the user. The management program and application programstored in the first memory 909 may be updated or corrected to a newlydownloaded program. Furthermore, the storage of the stared managementprogram and application program is maintained without being deleted evenif the power of the system is shut down. Therefore, when the power issupplied the programs may be executed without having to be newlydownloaded once again.

The application program for providing data service according to thepresent invention may either be initially stored in the first memory 909upon the shipping of the receiving system, or be stored in the first 909after being downloaded. The application program for the data service(i.e., the data service providing application program) stored in thefirst memory 909 may also be deleted, updated, and corrected.Furthermore, the data service providing application program may bedownloaded and executed along with the data service data each time thedata service data are being received.

When a data service request is transmitted through the user interface,the data broadcasting application manager 913 operates the correspondingapplication program stored in the first memory 909 so as to process therequested data, thereby providing the user with the requested dataservice. And, in order to provide such data service, the databroadcasting application manager 913 supports the graphic user interface(GUI). Herein, the data service may be provided in the form of text (orshort message service (SMS)), voice message, still image, and movingimage. The data broadcasting application manager 913 may be providedwith a platform for executing the application program stored in thefirst memory 909. The platform may be, for example, a Java virtualmachine for executing the Java program. Hereinafter, an example of thedata broadcasting application manager 913 executing the data serviceproviding application program stored in the first memory 909, so as toprocess the data service data stored in the second memory 911, therebyproviding the user with the corresponding data service will now bedescribed in detail.

Assuming that the data service corresponds to a traffic informationservice, the data service according to the present invention is providedto the user of a receiving system that is not equipped with anelectronic map and/or a GPS system in the form of at least one of a text(or short message service (SMS)), a voice message, a graphic message, astill image, and a moving image. In this case, is a GPS module ismounted on the receiving system shown in FIG. 16, the GPS modulereceives satellite signals transmitted from a plurality of low earthorbit satellites and extracts the current position (or location)information (e.g., longitude, latitude, altitude), thereby outputtingthe extracted information to the data broadcasting application manager913.

At this point, it is assumed that the electronic map includinginformation on each link and nod and other diverse graphic informationare stored in one of the second memory 911, the first memory 909, andanother memory that is not shown. More specifically, according to therequest made by the data broadcasting application manager 913, the dataservice data stored in the second memory 911 are read and inputted tothe data broadcasting application manager 913. The data broadcastingapplication manager 913 translates (or deciphers) the data service dataread from the second memory 911, thereby extracting the necessaryinformation according to the contents of the message and/or a controlsignal.

FIG. 17 illustrates a block diagram showing the structure of a digitalbroadcast (or television) receiving system according to anotherembodiment of the present invention. Referring to FIG. 17, the digitalbroadcast receiving system includes a tuner 1001, a demodulating unit1002, a demultiplexer 1003, a first descrambler 1004, an audio decoder1005, a video decoder 1005, a second descrambler 1007, an authenticationunit 1008, a native TV application manager 1009, a channel manager 1010,a channel map 1011, a first memory 1012, a data decoder 1013, a secondmemory 1014, a system manager 1015, a data broadcasting applicationmanager 1016, a storage controller 1017, a third memory 1018, and atelecommunication module 1019. Herein, the third memory 1018 is a massstorage device, such as a hard disk drive (HDD) or a memory chip. Also,during the description of the digital broadcast (or television or DTV)receiving system shown in FIG. 17, the components that are identical tothose of the digital broadcast receiving system of FIG. 16 will beomitted for simplicity.

As described above, in order to provide services for preventing illegalduplication (or copies) or illegal viewing of the enhanced data and/ormain data that are transmitted by using a broadcast network, and toprovide paid broadcast services, the transmitting system may generallyscramble and transmit the broadcast contents. Therefore, the receivingsystem needs to descrample the scrambled broadcast contents in order toprovide the user with the proper broadcast contents. Furthermore, thereceiving system may generally be processed with an authenticationprocess with an anuthnetication means before the descrambling process.Hereinafter, the receiving system including an authentication means anda descrambling means according to an embodiment of the present inventionwill now be described in detail.

According to the present invention, the receiving system may be providedwith a descrambling means receiving scrambled broadcasting contents andan authentication means authenticating (or verifying) whether thereceiving system is entitled to receive the descrambled contents.Hereinafter, the descrambling means will be referred to as first andsecond descramblers 1004 and 1007, and the authentication means will bereferred to as an authentication unit 1008. Such naming of thecorresponding components is merely exemplary and is not limited to theterms suggested in the description of the present invention. Forexample, the units may also be referred to as a decryptor. Although FIG.17 illustrates an example of the descramblers 1004 and 1007 and theauthentication unit 1008 being provided inside the receiving system,each of the descramblers 1004 and 1007 and the authentication unit 1008may also be separately provided in an internal or external module.Herein, the module may include a slot type, such as a SD or CF memory, amemory stick type, a USB type, and so on, and may be detachably fixed tothe receiving system.

As described above, when the authentication process is performedsuccessfully by the authentication unit 1008, the scrambled broadcastingcontents are descrambled by the descramblers 1004 and 1007, therebybeing provided to the user. At this point, a variety of theauthentication method and descrambling method may be used herein.However, an agreement on each corresponding method should be madebetween the receiving system and the transmitting system. Hereinafter,the authentication and descrambling methods will now be described, andthe description of identical components or process steps will be omittedfor simplicity.

The receiving system including the authentication unit 1008 and thedescramblers 1004 and 1007 will now be described in detail. Thereceiving system receives the scrambled broadcasting contents throughthe tuner 1001 and the demodulating unit 1002. Then, the system manager1015 decides whether the received broadcasting contents have beenscrambled. Herein, the demodulating unit 1002 may be included as ademodulating means according to embodiments of the present invention asdescribed in FIG. 11 and FIG. 15. However, the present invention is notlimited to the examples given in the description set forth herein. Ifthe system manager 1015 decides that the received broadcasting contentshave been scrambled, then the system manager 1015 controls the system tooperate the authentication unit 1008. As described above, theauthentication unit 1008 performs an authentication process in order todecide whether the receiving system according to the present inventioncorresponds to a legitimate host entitled to receive the paidbroadcasting service. Herein, the authentication process may vary inaccordance with the authentication methods.

For example, the authentication unit 1008 may perform the authenticationprocess by comparing an IP address of an IP datagram within the receivedbroadcasting contents with a specific address of a corresponding host.At this point, the specific address of the corresponding receivingsystem (or host) may be a MAC address. More specifically, theauthentication unit 1008 may extract the IP address from thedecapsulated IP datagram, thereby obtaining the receiving systeminformation that is mapped with the IP address. At this point, thereceiving system should be provided, in advance, with information (e.g.,a table format) that can map the IP address and the receiving systeminformation. Accordingly, the authentication unit 1008 performs theauthentication process by determining the conformity between the addressof the corresponding receiving system and the system information of thereceiving system that is mapped with the IP address. In other words, ifthe authentication unit 1008 determines that the two types ofinformation conform to one another, then the authentication unit 1008determines that the receiving system is entitled to receive thecorresponding broadcasting contents.

In another example, standardized identification information is definedin advance by the receiving system and the transmitting system. Then,the identification information of the receiving system requesting thepaid broadcasting service is transmitted by the transmitting system.Thereafter, the receiving system determines whether the receivedidentification information conforms with its own unique identificationnumber, so as to perform the authentication process. More specifically,the transmitting system creates a database for storing theidentification information (or number) of the receiving systemrequesting the paid broadcasting service. Then, if the correspondingbroadcasting contents are scrambled, the transmitting system includesthe identification information in the EMM, which is then transmitted tothe receiving system.

If the corresponding broadcasting contents are scrambled, messages(e.g., entitlement control message (ECM), entitlement management message(EMM)), such as the CAS information, mode information, message positioninformation, that are applied to the scrambling of the broadcastingcontents are transmitted through a corresponding data header or antherdata packet. The ECM may include a control word (CW) used for scramblingthe broadcasting contents. At this point, the control word may beencoded with an authentication key. The EMM may include anauthentication key and entitlement information of the correspondingdata. Herein, the authentication key may be encoded with a receivingsystem-specific distribution key. In other words, assuming that theenhanced data are scrambled by using the control word, and that theauthentication information and the descrambling information aretransmitted from the transmitting system, the transmitting systemencodes the CW with the authentication key and, then, includes theencoded CW in the entitlement control message (ECM), which is thentransmitted to the receiving system. Furthermore, the transmittingsystem includes the authentication key used for encoding the CW and theentitlement to receive data (or services) of the receiving system (i.e.,a standardized serial number of the receiving system that is entitled toreceive the corresponding broadcasting service or data) in theentitlement management message (EMM), which is then transmitted to thereceiving system.

Accordingly, the authentication unit 1008 of the receiving systemextracts the identification information of the receiving system and theidentification information included in the EMM of the broadcastingservice that is being received. Then, the authentication unit 1008determines whether the identification information conform to each other,so as to perform the authentication process. More specifically, if theauthentication unit 1008 determines that the information conform to eachother, then the authentication unit 1008 eventually determines that thereceiving system is entitled to receive the request broadcastingservice.

In yet another example, the authentication unit 1008 of the receivingsystem may be detachably fixed to an external module. In this case, thereceiving system is interfaced with the external module through a commoninterface (CI). In other words, the external module may receive the datascrambled by the receiving system through the common interface, therebyperforming the descrambling process of the received data. Alternatively,the external module may also transmit only the information required forthe descrambling process to the receiving system. The common interfaceis configured on a physical layer and at least one protocol layer.Herein, in consideration of any possible expansion of the protocol layerin a later process, the corresponding protocol layer may be configuredto have at least one layer that can each provide an independentfunction.

The external module may either consist of a memory or card havinginformation on the key used for the scrambling process and otherauthentication information but not including any descrambling function,or consist of a card having the above-mentioned key information andauthentication information and including the descrambling function. Boththe receiving system and the external module should be authenticated inorder to provide the user with the paid broadcasting service provided(or transmitted) from the transmitting system. Therefore, thetransmitting system can only provide the corresponding paid broadcastingservice to the authenticated pair of receiving system and externalmodule.

Additionally, an authentication process should also be performed betweenthe receiving system and the external module through the commoninterface. More specifically, the module may communicate with the systemmanager 1015 included in the receiving system through the commoninterface, thereby authenticating the receiving system. Alternatively,the receiving system may authenticate the module through the commoninterface. Furthermore, during the authentication process, the modulemay extract the unique ID of the receiving system and its own unique IDand transmit the extracted IDs to the transmitting system. Thus, thetransmitting system may use the transmitted ID values as informationdetermining whether to start the requested service or as paymentinformation. Whenever necessary, the system manager 1015 transmits thepayment information to the remote transmitting system through thetelecommunication module 1019.

The authentication unit 1008 authenticates the corresponding receivingsystem and/or the external module. Then, if the authentication processis successfully completed, the authentication unit 1008 certifies thecorresponding receiving system and/or the external module as alegitimate system and/or module entitled to receive the requested paidbroadcasting service. In addition, the authentication unit 1008 may alsoreceive authentication-associated information from a mobiletelecommunications service provider to which the user of the receivingsystem is subscribed, instead of the transmitting system providing therequested broadcasting service. In this case, theauthentication-association information may either be scrambled by thetransmitting system providing the broadcasting service and, then,transmitted to the user through the mobile telecommunications serviceprovider, or be directly scrambled and transmitted by the mobiletelecommunications service provider. Once the authentication process issuccessfully completed by the authentication unit 1008, the receivingsystem may descramble the scrambled broadcasting contents received fromthe transmitting system. At this point, the descrambling process isperformed by the first and second descramblers 1004 and 1007. Herein,the first and second descramblers 1004 and 1007 may be included in aninternal module or an external module of the receiving system.

The receiving system is also provided with a common interface forcommunicating with the external module including the first and seconddescramblers 1004 and 1007, so as to perform the descrambling process.More specifically, the first and second descramblers 1004 and 1007 maybe included in the module or in the receiving system in the form ofhardware, middleware or software. Herein, the descramblers 1004 and 1007may be included in any one of or both of the module and the receivingsystem. If the first and second descramblers 1004 and 1007 are providedinside the receiving system, it is advantageous to have the transmittingsystem (i.e., at least any one of a service provider and a broadcaststation) scramble the corresponding data using the same scramblingmethod.

Alternatively, if the first and second descramblers 1004 and 1007 areprovided in the external module, it is advantageous to have eachtransmitting system scramble the corresponding data using differentscrambling methods. In this case, the receiving system is not requiredto be provided with the descrambling algorithm corresponding to eachtransmitting system. Therefore, the structure and size of receivingsystem may be simplified and more compact. Accordingly, in this case,the external module itself may be able to provide CA functions, whichare uniquely and only provided by each transmitting systems, andfunctions related to each service that is to be provided to the user.The common interface enables the various external modules and the systemmanager 1015, which is included in the receiving system, to communicatewith one another by a single communication method. Furthermore, sincethe receiving system may be operated by being connected with at leastone or more modules providing different services, the receiving systemmay be connected to a plurality of modules and controllers.

In order to maintain successful communication between the receivingsystem and the external module, the common interface protocol includes afunction of periodically checking the status of the oppositecorrespondent. By using this function, the receiving system and theexternal module is capable of managing the status of each oppositecorrespondent. This function also reports the user or the transmittingsystem of any malfunction that may occur in any one of the receivingsystem and the external module and attempts the recovery of themalfunction.

In yet another example, the authentication process may be performedthrough software. More specifically, when a memory card having CASsoftware downloaded, for example, and stored therein in advanced isinserted in the receiving system, the receiving system receives andloads the CAS software from the memory card so as to perform theauthentication process. In this example, the CAS software is read outfrom the memory card and stored in the first memory 1012 of thereceiving system. Thereafter, the CAS software is operated in thereceiving system as an application program. According to an embodimentof the present invention, the CAS software is mounted on (or stored) ina middleware platform and, then executed. A Java middleware will begiven as an example of the middleware included in the present invention.Herein, the CAS software should at least include information requiredfor the authentication process and also information required for thedescrambling process.

Therefore, the authentication unit 1008 performs authenticationprocesses between the transmitting system and the receiving system andalso between the receiving system and the memory card. At this point, asdescribed above, the memory card should be entitled to receive thecorresponding data and should include information on a normal receivingsystem that can be authenticated. For example, information on thereceiving system may include a unique number, such as a standardizedserial number of the corresponding receiving system. Accordingly, theauthentication unit 1008 compares the standardized serial numberincluded in the memory card with the unique information of the receivingsystem, thereby performing the authentication process between thereceiving system and the memory card.

If the CAS software is first executed in the Java middleware base, thenthe authentication between the receiving system and the memory card isperformed. For example, when the unique number of the receiving systemstored in the memory card conforms to the unique number of the receivingsystem read from the system manager 1015, then the memory card isverified and determined to be a normal memory card that may be used inthe receiving system. At this point, the CAS software may either beinstalled in the first memory 1012 upon the shipping of the presentinvention, or be downloaded to the first memory 1012 from thetransmitting system or the module or memory card, as described above.Herein, the descrambling function may be operated by the databroadcasting application manger 1016 as an application program.

Thereafter, the CAS software parses the EMM/ECM packets outputted fromthe demultiplexer 1003, so as to verify whether the receiving system isentitled to receive the corresponding data, thereby obtaining theinformation required for descrambling (i.e., the CW) and providing theobtained CW to the descramblers 1004 and 1007. More specifically, theCAS software operating in the Java middleware platform first reads outthe unique (or serial) number of the receiving system from thecorresponding receiving system and compares it with the unique number ofthe receiving system transmitted through the EMM, thereby verifyingwhether the receiving system is entitled to receive the correspondingdata. Once the receiving entitlement of the receiving system isverified, the corresponding broadcasting service information transmittedto the ECM and the entitlement of receiving the correspondingbroadcasting service are used to verify whether the receiving system isentitled to receive the corresponding broadcasting service. Once thereceiving system is verified to be entitled to receive the correspondingbroadcasting service, the authentication key transmitted to the EMM isused to decode (or decipher) the encoded CW, which is transmitted to theECM, thereby transmitting the decoded CW to the descramblers 1004 and1007. Each of the descramblers 1004 and 1007 uses the CW to descramblethe broadcasting service.

Meanwhile, the CAS software stored in the memory card may be expanded inaccordance with the paid service which the broadcast station is toprovide. Additionally, the CAS software may also include otheradditional information other than the information associated with theauthentication and descrambling. Furthermore, the receiving system maydownload the CAS software from the transmitting system so as to upgrade(or update) the CAS software originally stored in the memory card. Asdescribed above, regardless of the type of broadcast receiving system,as long as an external memory interface is provided, the presentinvention may embody a CAS system that can meet the requirements of alltypes of memory card that may be detachably fixed to the receivingsystem. Thus, the present invention may realize maximum performance ofthe receiving system with minimum fabrication cost, wherein thereceiving system may receive paid broadcasting contents such asbroadcast programs, thereby acknowledging and regarding the variety ofthe receiving system. Moreover, since only the minimum applicationprogram interface is required to be embodied in the embodiment of thepresent invention, the fabrication cost may be minimized, therebyeliminating the manufacturer's dependence on CAS manufacturers.Accordingly, fabrication costs of CAS equipments and management systemsmay also be minimized.

Meanwhile, the descramblers 1004 and 1007 may be included in the moduleeither in the form of hardware or in the form of software. In this case,the scrambled data that being received are descrambled by the module andthen demodulated. Also, if the scrambled data that are being receivedare stored in the third memory 1018, the received data may bedescrambled and then stored, or stored in the memory at the point ofbeing received and then descrambled later on prior to being played (orreproduced). Thereafter, in case scramble/descramble algorithms areprovided in the storage controller 1017, the storage controller 1017scrambles the data that are being received once again and then storesthe re-scrambled data to the third memory 1018.

In yet another example, the descrambled broadcasting contents(transmission of which being restricted) are transmitted through thebroadcasting network. Also, information associated with theauthentication and descrambling of data in order to disable thereceiving restrictions of the corresponding data are transmitted and/orreceived through the telecommunications module 1019. Thus, the receivingsystem is able to perform reciprocal (or two-way) communication. Thereceiving system may either transmit data to the telecommunicationmodule within the transmitting system or be provided with the data fromthe telecommunication module within the transmitting system. Herein, thedata correspond to broadcasting data that are desired to be transmittedto or from the transmitting system, and also unique information (i.e.,identification information) such as a serial number of the receivingsystem or MAC address.

The telecommunication module 1019 included in the receiving systemprovides a protocol required for performing reciprocal (or two-way)communication between the receiving system, which does not support thereciprocal communication function, and the telecommunication moduleincluded in the transmitting system. Furthermore, the receiving systemconfigures a protocol data unit (PDU) using a tag-length-value (TLV)coding method including the data that are to be transmitted and theunique information (or ID information). Herein, the tag field includesindexing of the corresponding PDU. The length field includes the lengthof the value field. And, the value field includes the actual data thatare to be transmitted and the unique number (e.g., identificationnumber) of the receiving system.

The receiving system may configure a platform that is equipped with theJava platform and that is operated after downloading the Javaapplication of the transmitting system to the receiving system throughthe network. In this case, a structure of downloading the PDU includingthe tag field arbitrarily defined by the transmitting system from astorage means included in the receiving system and then transmitting thedownloaded PDU to the telecommunication module 1019 may also beconfigured. Also, the PDU may be configured in the Java application ofthe receiving system and then outputted to the telecommunication module1019. The PDU may also be configured by transmitting the tag value, theactual data that are to be transmitted, the unique information of thecorresponding receiving system from the Java application and byperforming the TLV coding process in the receiving system. Thisstructure is advantageous in that the firmware of the receiving systemis not required to be changed even if the data (or application) desiredby the transmitting system is added.

The telecommunication module within the transmitting system eithertransmits the PDU received from the receiving system through a wirelessdata network or configures the data received through the network into aPDU which is transmitted to the host. At this point, when configuringthe PDU that is to be transmitted to the host, the telecommunicationmodule within the transmitting end may include unique information (e.g.,IP address) of the transmitting system which is located in a remotelocation. Additionally, in receiving and transmitting data through thewireless data network, the receiving system may be provided with acommon interface, and also provided with a WAP, CDMA 1×EV-DO, which canbe connected through a mobile telecommunication base station, such asCDMA and GSM, and also provided with a wireless LAN, mobile internet,WiBro, WiMax, which can be connected through an access point. Theabove-described receiving system corresponds to the system that is notequipped with a telecommunication function. However, a receiving systemequipped with telecommunication function does not require thetelecommunication module 1019.

The broadcasting data being transmitted and received through theabove-described wireless data network may include data required forperforming the function of limiting data reception. Meanwhile, thedemultiplexer 1003 receives either the real-time data outputted from thedemodulating unit 1002 or the data read from the third memory 1018,thereby performing demultiplexing. In this embodiment of the presentinvention, the demultiplexer 1003 performs demultiplexing on theenhanced data packet. Similar process steps have already been describedearlier in the description of the present invention. Therefore, adetailed of the process of demultiplexing the enhanced data will beomitted for simplicity.

The first descrambler 1004 receives the demultiplexed signals from thedemultiplexer 1003 and then descrambles the received signals. At thispoint, the first descrambler 1004 may receive the authentication resultreceived from the authentication unit 1008 and other data required forthe descrambling process, so as to perform the descrambling process. Theaudio decoder 1005 and the video decoder 1006 receive the signalsdescrambled by the first descrambler 1004, which are then decoded andoutputted. Alternatively, if the first descrambler 1004 did not performthe descrambling process, then the audio decoder 1005 and the videodecoder 1006 directly decode and output the received signals. In thiscase, the decoded signals are received and then descrambled by thesecond descrambler 1007 and processed accordingly.

As described above, the present invention has the following advantages.More specifically, the present invention is highly protected against (orresistant to) any error that may occur when transmitting additional datathrough a channel. And, the present invention is also highly compatibleto the conventional receiving system. Moreover, the present inventionmay also receive the additional data without any error even in channelshaving severe ghost effect and noise.

Additionally, by grouping a plurality of enhanced data packets, bylayering the group to a plurality of areas when multiplexing the groupwith the main data and transmitting the multiplexed data, and byidentifying the data type, processing method, and so on according to thecharacteristic of each layered area, the receiving function of thereceiving system may be enhanced. Moreover, by performing at least anyone of the error correction coding process and the error detectioncoding process on the enhanced data, and by performing a row permutationprocess, the enhanced data may become robust, thereby being able to takestrong countermeasures against the constantly changing channelenvironment.

Furthermore, by performing additional error correction encoding,randomizing, and deinterleaving processes before multiplexing theenhanced data and the main data, the structure of the digital televisiontransmitting system may be simplified. Finally, the present invention iseven more effective in providing robustness when applied to mobile andportable receivers, which are also liable to a frequent change inchannel and which require robustness against intense noise.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-40. (canceled)
 41. A receiving system, comprising: a signal receiving unit for receiving a broadcast signal, the broadcast signal comprising signaling information in a data group, wherein the data group results from a portion of a Reed-Solomon (RS) frame which comprises K (K>1) number of packets including A (A>1) number of bytes of mobile data, an RS parity data generated based on the K number of packets, and a Cyclic Redundancy Check (CRC) checksum data generated based on mobile data in the K number of packets or the RS parity data, and the data group has a plurality of known data sequences and has a plurality of segments with different number of bytes for the mobile data; a demodulating unit for demodulating the received broadcast signal; a first-decoder for decoding the demodulated broadcast signal; and a second-decoder for decoding the first-decoded broadcast signal, wherein at least two of the plurality of known data sequences have different lengths and the signaling information is inserted between the plurality of known data sequences.
 42. The receiving system of claim 41, wherein the second-decoder corrects errors generated in the mobile data by performing CRC decoding and RS decoding.
 43. The receiving system of claim 41, wherein the signal receiving unit receives the first data by turning power on or off based on the signaling information.
 44. The receiving system of claim 41, further comprising an equalizer for compensating for channel distortion using the plurality of known data sequences.
 45. A method of processing broadcast data in a receiving system, the method comprising: receiving a broadcast signal, the broadcast signal comprising signaling information in a data group, wherein the data group results from a portion of a Reed-Solomon (RS) frame which comprises K (K>1) number of packets including A (A>1) number of bytes of mobile data, an RS parity data generated based on the K number of packets, and a Cyclic Redundancy Check (CRC) checksum data generated based on mobile data in the K number of packets or the RS parity data, and the data group has a plurality of known data sequences and has a plurality of segments with different number of bytes for the mobile data; demodulating the received broadcast signal; first decoding the demodulated broadcast signal; and second decoding the first-decoded broadcast signal, wherein at least two of the plurality of known data sequences have different lengths and the signaling information is inserted between the plurality of known data sequences.
 46. The method of claim 45, wherein second-decoding the first-decoded broadcast signal corrects errors generated in the mobile data by performing CRC decoding and RS decoding.
 47. The method of claim 45, wherein receiving the broadcast signal further comprises receiving the first data by turning power on or off based on the signaling information.
 48. The method of claim 45, wherein the signaling information further comprises multiplex information.
 49. The method of claim 45, further comprising compensating for channel distortion using the plurality of known data sequences. 